{ "checked": "2026-10", "cards": [ { "front": "SIP", "back": "Application signaling for sessions. The base specification is RFC 3261.", "href": "rooms/T01-what-sip-is.html", "room": "What SIP is for" }, { "front": "SDP", "back": "Describes media. Offer/answer is RFC 3264.", "href": "rooms/T01-what-sip-is.html", "room": "What SIP is for" }, { "front": "RTP", "back": "Carries the media packets after the answer names the port.", "href": "rooms/T01-what-sip-is.html", "room": "What SIP is for" }, { "front": "100 Trying", "back": "Hop-by-hop provisional. A stateful proxy generates it and does not relay one.", "href": "rooms/T01-what-sip-is.html", "room": "What SIP is for" }, { "front": "5060", "back": "Default port for SIP over UDP and SIP over TCP.", "href": "rooms/T01-prereq-network.html", "room": "Ports, transports, and where a request can go" }, { "front": "5061", "back": "Default port for SIP over TLS.", "href": "rooms/T01-prereq-network.html", "room": "Ports, transports, and where a request can go" }, { "front": "Content-Length", "back": "On a stream transport, this is how the parser finds the end of the message.", "href": "rooms/T01-prereq-network.html", "room": "Ports, transports, and where a request can go" }, { "front": "WS / WSS", "back": "WebSocket transport tokens from RFC 7118. The SIP methods do not change.", "href": "rooms/T01-prereq-network.html", "room": "Ports, transports, and where a request can go" }, { "front": "tel:+15551212", "back": "A global telephone URI. The scheme is RFC 3966.", "href": "rooms/T01-e164-and-uris.html", "room": "E.164, sip URIs, and tel URIs" }, { "front": "user=phone", "back": "The sip user part should be read as a phone number.", "href": "rooms/T01-e164-and-uris.html", "room": "E.164, sip URIs, and tel URIs" }, { "front": "E.164", "back": "The ITU-T numbering plan. The URI citation in this course is RFC 3966.", "href": "rooms/T01-e164-and-uris.html", "room": "E.164, sip URIs, and tel URIs" }, { "front": "Request-URI", "back": "Where this hop sends the request. Retargeting changes it and leaves To in place.", "href": "rooms/T01-e164-and-uris.html", "room": "E.164, sip URIs, and tel URIs" }, { "front": "Standards Track", "back": "The status of RFC 3261. It is the base specification.", "href": "rooms/T01-reading-an-rfc.html", "room": "How to read an RFC" }, { "front": "Section 20", "back": "Header field catalog, including the compact names defined there.", "href": "rooms/T01-reading-an-rfc.html", "room": "How to read an RFC" }, { "front": "Section 21", "back": "Response code catalog.", "href": "rooms/T01-reading-an-rfc.html", "room": "How to read an RFC" }, { "front": "Section 25", "back": "ABNF. Use it when a message looks almost right.", "href": "rooms/T01-reading-an-rfc.html", "room": "How to read an RFC" }, { "front": "RFC 5411", "back": "Informational hitchhiker's guide. A map, not the base spec.", "href": "rooms/T01-hitchhiker.html", "room": "The hitchhiker guide is a map" }, { "front": "RFC 3262", "back": "PRACK and reliable provisional responses.", "href": "rooms/T01-hitchhiker.html", "room": "The hitchhiker guide is a map" }, { "front": "RFC 4028", "back": "Session timers. Not a substitute chapter inside 5411.", "href": "rooms/T01-hitchhiker.html", "room": "The hitchhiker guide is a map" }, { "front": "RFC 6026", "back": "Corrects INVITE 2xx transaction handling after 3261.", "href": "rooms/T01-hitchhiker.html", "room": "The hitchhiker guide is a map" }, { "front": "IETF Trust", "back": "Legal provisions for IETF documents. Read them before copying protocol text.", "href": "rooms/T01-licensing.html", "room": "Licenses, codecs, and what you may copy" }, { "front": "Opus", "back": "RFC 6716, plus the Opus license page and the IETF IPR disclosures.", "href": "rooms/T01-licensing.html", "room": "Licenses, codecs, and what you may copy" }, { "front": "G.711", "back": "ITU-T recommendation for PCMU and PCMA. Not an IETF RFC.", "href": "rooms/T01-licensing.html", "room": "Licenses, codecs, and what you may copy" }, { "front": "G.729", "back": "ITU-T recommendation. Verify patent status. Do not state an expiry date.", "href": "rooms/T01-licensing.html", "room": "Licenses, codecs, and what you may copy" }, { "front": "z9hG4bK", "back": "Magic cookie at the start of a branch parameter.", "href": "rooms/T01-first-message.html", "room": "Reading the first INVITE" }, { "front": "Max-Forwards: 70", "back": "The value a UAC SHOULD put on a request it originates.", "href": "rooms/T01-first-message.html", "room": "Reading the first INVITE" }, { "front": "No To tag", "back": "An initial request is outside a dialog, so To has no tag.", "href": "rooms/T01-first-message.html", "room": "Reading the first INVITE" }, { "front": "RFC 5737", "back": "Documentation IPv4 ranges used for the examples in this course.", "href": "rooms/T01-first-message.html", "room": "Reading the first INVITE" }, { "front": "UAC", "back": "Creates a request. Defined with the rest of the user-agent rules.", "href": "rooms/T02-roles.html", "room": "Roles a trace is actually showing" }, { "front": "Stateful proxy", "back": "Transaction state, own Via branch, own 100 Trying.", "href": "rooms/T02-roles.html", "room": "Roles a trace is actually showing" }, { "front": "Redirect", "back": "3xx and a Contact, then it is out of the call.", "href": "rooms/T02-roles.html", "room": "Roles a trace is actually showing" }, { "front": "B2BUA", "back": "UAS plus UAC. Expect a second dialog. See RFC 7092.", "href": "rooms/T02-roles.html", "room": "Roles a trace is actually showing" }, { "front": "INVITE / ACK / BYE", "back": "Set up, complete the handshake, and end a confirmed dialog.", "href": "rooms/T02-methods-and-codes.html", "room": "Methods and status codes" }, { "front": "CANCEL", "back": "Abandon an unanswered INVITE. It is not BYE.", "href": "rooms/T02-methods-and-codes.html", "room": "Methods and status codes" }, { "front": "401 vs 407", "back": "UAS or registrar challenge versus proxy challenge.", "href": "rooms/T02-methods-and-codes.html", "room": "Methods and status codes" }, { "front": "1xx", "back": "Provisional. The transaction is still waiting for a final response.", "href": "rooms/T02-methods-and-codes.html", "room": "Methods and status codes" }, { "front": "v / f / t / i", "back": "Via, From, To, Call-ID.", "href": "rooms/T02-headers-and-compact.html", "room": "Headers and compact forms" }, { "front": "m / l / c / k", "back": "Contact, Content-Length, Content-Type, Supported.", "href": "rooms/T02-headers-and-compact.html", "room": "Headers and compact forms" }, { "front": "o and u", "back": "Event and Allow-Events. RFC 6665.", "href": "rooms/T02-headers-and-compact.html", "room": "Headers and compact forms" }, { "front": "r and b", "back": "Refer-To and Referred-By. RFC 3515.", "href": "rooms/T02-headers-and-compact.html", "room": "Headers and compact forms" }, { "front": "Branch", "back": "Transaction identifier. Cookie z9hG4bK plus a unique token.", "href": "rooms/T02-transactions.html", "room": "Transactions and the branch cookie" }, { "front": "Retransmission", "back": "Same message, same branch, sent again by the transaction timer.", "href": "rooms/T02-transactions.html", "room": "Transactions and the branch cookie" }, { "front": "2xx ACK", "back": "New transaction, new branch, end to end. CSeq number matches the INVITE.", "href": "rooms/T02-transactions.html", "room": "Transactions and the branch cookie" }, { "front": "Timer B", "back": "INVITE transaction timeout, 64 times T1. No ACK is generated.", "href": "rooms/T02-transactions.html", "room": "Transactions and the branch cookie" }, { "front": "Call-ID + tags", "back": "The dialog id. Both tags are required once the dialog exists.", "href": "rooms/T02-dialogs.html", "room": "Dialog identity" }, { "front": "Early", "back": "Provisional response with a To tag. Not confirmed yet.", "href": "rooms/T02-dialogs.html", "room": "Dialog identity" }, { "front": "Confirmed", "back": "A 2xx to INVITE. BYE is now the teardown.", "href": "rooms/T02-dialogs.html", "room": "Dialog identity" }, { "front": "CSeq", "back": "Increments for new in-dialog requests. ACK and CANCEL keep the INVITE number.", "href": "rooms/T02-dialogs.html", "room": "Dialog identity" }, { "front": "T1 = 500 ms", "back": "Default RTT estimate. Timer A starts here on UDP.", "href": "rooms/T02-three-clocks.html", "room": "T1, the transaction timeout, and Timer C" }, { "front": "64*T1", "back": "Timer B for INVITE and Timer F for non-INVITE.", "href": "rooms/T02-three-clocks.html", "room": "T1, the transaction timeout, and Timer C" }, { "front": "T2 = 4 s, T4 = 5 s", "back": "Retransmit cap, and how long a message may remain in the network.", "href": "rooms/T02-three-clocks.html", "room": "T1, the transaction timeout, and Timer C" }, { "front": "Timer C", "back": "Proxy timer for an unanswered INVITE. More than 3 minutes.", "href": "rooms/T02-three-clocks.html", "room": "T1, the transaction timeout, and Timer C" }, { "front": "Via transport", "back": "UDP, TCP, TLS, WS, or WSS for this hop.", "href": "rooms/T02-transports.html", "room": "UDP, TCP, TLS, and WebSocket" }, { "front": "received / rport", "back": "Response address and, with RFC 3581, the source port.", "href": "rooms/T02-transports.html", "room": "UDP, TCP, TLS, and WebSocket" }, { "front": "session protocol sipv2", "back": "Dial-peer command that selects SIP for that peer.", "href": "rooms/T02-transports.html", "room": "UDP, TCP, TLS, and WebSocket" }, { "front": "ip address trusted list", "back": "Sources allowed to present SIP. See the toll-fraud guidance.", "href": "rooms/T02-transports.html", "room": "UDP, TCP, TLS, and WebSocket" }, { "front": "Non-2xx ACK", "back": "Same branch as that hop's INVITE. Generated by the client transaction.", "href": "rooms/T03-two-acks.html", "room": "Two different ACK rules" }, { "front": "2xx ACK", "back": "New branch, dialog route set, end to end.", "href": "rooms/T03-two-acks.html", "room": "Two different ACK rules" }, { "front": "CSeq: 1 ACK", "back": "Same number as the INVITE. The method token changes to ACK.", "href": "rooms/T03-two-acks.html", "room": "Two different ACK rules" }, { "front": "603 then ACK", "back": "Forward the 603. ACK it on this hop. Do not relay the ACK.", "href": "rooms/T03-two-acks.html", "room": "Two different ACK rules" }, { "front": "Record-Route", "back": "Inserted by a proxy that must see later requests in the dialog.", "href": "rooms/T03-record-route.html", "room": "Record-Route and the route set" }, { "front": "lr", "back": "Required on that URI. It selects loose routing.", "href": "rooms/T03-record-route.html", "room": "Record-Route and the route set" }, { "front": "UAC reverses", "back": "Response Record-Route, reversed, becomes the caller's route set.", "href": "rooms/T03-record-route.html", "room": "Record-Route and the route set" }, { "front": "Contact", "back": "The remote target. It becomes the mid-dialog Request-URI.", "href": "rooms/T03-record-route.html", "room": "Record-Route and the route set" }, { "front": "Supported: 100rel", "back": "The UAC can do reliable provisionals.", "href": "rooms/T03-prack.html", "room": "PRACK and reliable provisionals" }, { "front": "RSeq", "back": "Identifies the reliable provisional.", "href": "rooms/T03-prack.html", "room": "PRACK and reliable provisionals" }, { "front": "RAck", "back": "RSeq, then the CSeq number and method being acknowledged.", "href": "rooms/T03-prack.html", "room": "PRACK and reliable provisionals" }, { "front": "PRACK", "back": "A new transaction. Its success response is 200 OK, not ACK.", "href": "rooms/T03-prack.html", "room": "PRACK and reliable provisionals" }, { "front": "UPDATE", "back": "Session refresh or change. Own transaction. RFC 3311.", "href": "rooms/T03-update.html", "room": "UPDATE before the INVITE completes" }, { "front": "No ACK", "back": "200 OK finishes UPDATE. ACK is reserved for INVITE.", "href": "rooms/T03-update.html", "room": "UPDATE before the INVITE completes" }, { "front": "Early dialog", "back": "UPDATE can run before the first INVITE completes.", "href": "rooms/T03-update.html", "room": "UPDATE before the INVITE completes" }, { "front": "RFC 6141", "back": "Read this before changing the remote target.", "href": "rooms/T03-update.html", "room": "UPDATE before the INVITE completes" }, { "front": "Session-Expires", "back": "Seconds until the session must be refreshed, plus an optional refresher.", "href": "rooms/T03-session-timers.html", "room": "Session-Expires and 422" }, { "front": "Min-SE", "back": "Minimum interval. Never below 90 seconds.", "href": "rooms/T03-session-timers.html", "room": "Session-Expires and 422" }, { "front": "422", "back": "Session Interval Too Small. Retry with the Min-SE from the response.", "href": "rooms/T03-session-timers.html", "room": "Session-Expires and 422" }, { "front": "refresher", "back": "uac or uas. That side sends re-INVITE or UPDATE.", "href": "rooms/T03-session-timers.html", "room": "Session-Expires and 422" }, { "front": "CANCEL", "back": "Same branch as the unanswered INVITE. CSeq number unchanged.", "href": "rooms/T03-cancel-bye-reinvite.html", "room": "CANCEL, BYE, and re-INVITE" }, { "front": "487", "back": "Final response to the INVITE that was cancelled. Then ACK.", "href": "rooms/T03-cancel-bye-reinvite.html", "room": "CANCEL, BYE, and re-INVITE" }, { "front": "BYE", "back": "Ends a confirmed dialog. Higher CSeq. Both tags.", "href": "rooms/T03-cancel-bye-reinvite.html", "room": "CANCEL, BYE, and re-INVITE" }, { "front": "re-INVITE", "back": "Mid-dialog INVITE. See RFC 6141 if Contact changes the target.", "href": "rooms/T03-cancel-bye-reinvite.html", "room": "CANCEL, BYE, and re-INVITE" }, { "front": "Refer-To", "back": "The request the recipient should send. Compact form r.", "href": "rooms/T03-refer-replaces.html", "room": "REFER and Replaces" }, { "front": "202 Accepted", "back": "REFER was accepted. Watch NOTIFY for the real result.", "href": "rooms/T03-refer-replaces.html", "room": "REFER and Replaces" }, { "front": "Replaces", "back": "call-id, to-tag, from-tag of the dialog to take over.", "href": "rooms/T03-refer-replaces.html", "room": "REFER and Replaces" }, { "front": "sipfrag", "back": "A status line in the NOTIFY body, such as SIP/2.0 200 OK.", "href": "rooms/T03-refer-replaces.html", "room": "REFER and Replaces" }, { "front": "To on REGISTER", "back": "The address-of-record being bound.", "href": "rooms/T04-register.html", "room": "REGISTER and bindings" }, { "front": "Contact", "back": "The binding: where requests for that address-of-record can go.", "href": "rooms/T04-register.html", "room": "REGISTER and bindings" }, { "front": "423", "back": "Interval Too Brief. Read Min-Expires and retry.", "href": "rooms/T04-register.html", "room": "REGISTER and bindings" }, { "front": "Contact: *", "back": "With Expires: 0, removes all bindings for the address-of-record.", "href": "rooms/T04-register.html", "room": "REGISTER and bindings" }, { "front": "NAPTR", "back": "Selects the SIP service, such as SIP+D2U or SIP+D2T.", "href": "rooms/T04-dns-3263.html", "room": "Locating a server with RFC 3263" }, { "front": "SRV", "back": "Host and port for the selected service.", "href": "rooms/T04-dns-3263.html", "room": "Locating a server with RFC 3263" }, { "front": "A / AAAA", "back": "Addresses for the SRV target.", "href": "rooms/T04-dns-3263.html", "room": "Locating a server with RFC 3263" }, { "front": "Numeric IP", "back": "No domain lookup. Send to that address.", "href": "rooms/T04-dns-3263.html", "room": "Locating a server with RFC 3263" }, { "front": "lr", "back": "Loose routing. Pop Route, keep the Request-URI.", "href": "rooms/T04-loose-routing.html", "room": "Loose routing and Max-Forwards" }, { "front": "Max-Forwards", "back": "Starts at 70. Decremented by each proxy.", "href": "rooms/T04-loose-routing.html", "room": "Loose routing and Max-Forwards" }, { "front": "483", "back": "Too Many Hops. The request arrived with Max-Forwards 0.", "href": "rooms/T04-loose-routing.html", "room": "Loose routing and Max-Forwards" }, { "front": "482", "back": "Loop Detected from a Via loop, not from the hop budget.", "href": "rooms/T04-loose-routing.html", "room": "Loose routing and Max-Forwards" }, { "front": "reg-id", "back": "Identifies one flow. A new value is a new flow.", "href": "rooms/T04-outbound.html", "room": "Outbound, reg-id, and keepalives" }, { "front": "+sip.instance", "back": "URN for the UA instance, stable across flows.", "href": "rooms/T04-outbound.html", "room": "Outbound, reg-id, and keepalives" }, { "front": "CRLF keepalive", "back": "Double CRLF on connection-oriented transports. Single CRLF answers.", "href": "rooms/T04-outbound.html", "room": "Outbound, reg-id, and keepalives" }, { "front": "STUN keepalive", "back": "The UDP keepalive in the outbound specification.", "href": "rooms/T04-outbound.html", "room": "Outbound, reg-id, and keepalives" }, { "front": "Path", "back": "Inbound vector stored with the binding. RFC 3327.", "href": "rooms/T04-path-service-route.html", "room": "Path and Service-Route" }, { "front": "Service-Route", "back": "Outbound preloaded route from the registrar. RFC 3608.", "href": "rooms/T04-path-service-route.html", "room": "Path and Service-Route" }, { "front": "lr on Path", "back": "The edge URI is loose-routed, same as Record-Route.", "href": "rooms/T04-path-service-route.html", "room": "Path and Service-Route" }, { "front": "Preloaded Route", "back": "The UA puts Service-Route into Route on a new INVITE.", "href": "rooms/T04-path-service-route.html", "room": "Path and Service-Route" }, { "front": "pub-gruu", "back": "Stable URI for one UA instance.", "href": "rooms/T04-gruu.html", "room": "GRUU and a single instance" }, { "front": "temp-gruu", "back": "Instance URI that hides the address-of-record.", "href": "rooms/T04-gruu.html", "room": "GRUU and a single instance" }, { "front": "+sip.instance", "back": "The URN the registrar binds to those GRUUs.", "href": "rooms/T04-gruu.html", "room": "GRUU and a single instance" }, { "front": "gr", "back": "URI parameter that marks a GRUU.", "href": "rooms/T04-gruu.html", "room": "GRUU and a single instance" }, { "front": "Fork", "back": "One incoming INVITE, one client transaction per target.", "href": "rooms/T04-forking.html", "room": "Forking and early dialogs" }, { "front": "Early dialog", "back": "A To tag on a provisional response. One per branch.", "href": "rooms/T04-forking.html", "room": "Forking and early dialogs" }, { "front": "Multiple 200 OK", "back": "Forward each. The UAC ACKs each and may BYE the extras.", "href": "rooms/T04-forking.html", "room": "Forking and early dialogs" }, { "front": "6xx", "back": "Cancel the other pending branches. Do not start new ones.", "href": "rooms/T04-forking.html", "room": "Forking and early dialogs" }, { "front": "RFC 8866", "back": "Current SDP. It obsoletes RFC 4566. Trust the RFC Editor status banner.", "href": "rooms/T05-sdp-anatomy.html", "room": "The lines in an SDP body" }, { "front": "c=", "back": "Connection address where media should be sent.", "href": "rooms/T05-sdp-anatomy.html", "room": "The lines in an SDP body" }, { "front": "m=", "back": "One media stream: type, port, protocol, and payload types.", "href": "rooms/T05-sdp-anatomy.html", "room": "The lines in an SDP body" }, { "front": "a=", "back": "An attribute. After m=, it belongs to that stream.", "href": "rooms/T05-sdp-anatomy.html", "room": "The lines in an SDP body" }, { "front": "Same count", "back": "The answer has exactly as many m-lines as the offer.", "href": "rooms/T05-offer-answer-order.html", "room": "Same m-lines, same order" }, { "front": "Same order", "back": "Line n in the answer answers line n in the offer.", "href": "rooms/T05-offer-answer-order.html", "room": "Same m-lines, same order" }, { "front": "Port 0", "back": "Rejects that stream and keeps its position.", "href": "rooms/T05-offer-answer-order.html", "room": "Same m-lines, same order" }, { "front": "RFC 6337", "back": "Usage examples and the pitfalls of rebuilding SDP.", "href": "rooms/T05-offer-answer-order.html", "room": "Same m-lines, same order" }, { "front": "Encoding name", "back": "Match opus to opus even when the payload type numbers differ.", "href": "rooms/T05-rtpmap-fmtp.html", "room": "rtpmap names and fmtp parameters" }, { "front": "0 / 8 / 9 / 18", "back": "PCMU/8000, PCMA/8000, G722/8000, G729/8000.", "href": "rooms/T05-rtpmap-fmtp.html", "room": "rtpmap names and fmtp parameters" }, { "front": "G722/8000", "back": "RTP clock is 8000. Audio sample rate is 16 kHz.", "href": "rooms/T05-rtpmap-fmtp.html", "room": "rtpmap names and fmtp parameters" }, { "front": "fmtp", "back": "Parameters for one payload type. Do not guess unknown ones.", "href": "rooms/T05-rtpmap-fmtp.html", "room": "rtpmap names and fmtp parameters" }, { "front": "sendrecv", "back": "Send and receive. The usual active call.", "href": "rooms/T05-direction-hold.html", "room": "Direction attributes and hold" }, { "front": "sendonly", "back": "Send, and do not receive. A common hold.", "href": "rooms/T05-direction-hold.html", "room": "Direction attributes and hold" }, { "front": "recvonly", "back": "Receive only. The usual answer to sendonly.", "href": "rooms/T05-direction-hold.html", "room": "Direction attributes and hold" }, { "front": "inactive", "back": "Neither direction. Also a common hold.", "href": "rooms/T05-direction-hold.html", "room": "Direction attributes and hold" }, { "front": "m=audio 0", "back": "Rejects that audio stream. Keep proto and a format.", "href": "rooms/T05-port-zero.html", "room": "Port 0 rejects a stream" }, { "front": "Same index", "back": "A rejected line is still answered in its original position.", "href": "rooms/T05-port-zero.html", "room": "Port 0 rejects a stream" }, { "front": "No common codec", "back": "Port 0 on that m-line, not a deleted body.", "href": "rooms/T05-port-zero.html", "room": "Port 0 rejects a stream" }, { "front": "Offer port 0", "back": "The answer port is also 0.", "href": "rooms/T05-port-zero.html", "room": "Port 0 rejects a stream" }, { "front": "183 + SDP", "back": "Usual early-media pattern. Not true of every 183.", "href": "rooms/T05-early-media.html", "room": "Early media and 183" }, { "front": "180", "back": "Ringing. Local ringback when this message has no SDP.", "href": "rooms/T05-early-media.html", "room": "Early media and 183" }, { "front": "100rel", "back": "Makes a provisional response reliable. PRACK it.", "href": "rooms/T05-early-media.html", "room": "Early media and 183" }, { "front": "Two bodies", "back": "Compare 183 SDP with the 200 OK SDP before you lock the port.", "href": "rooms/T05-early-media.html", "room": "Early media and 183" }, { "front": "RFC 6337", "back": "Offer/answer usage and the mistakes to stop repeating.", "href": "rooms/T05-pitfalls-6337.html", "room": "Offer/answer pitfalls in RFC 6337" }, { "front": "sess-version", "back": "Increase it when the SDP changes.", "href": "rooms/T05-pitfalls-6337.html", "room": "Offer/answer pitfalls in RFC 6337" }, { "front": "Delayed offer", "back": "No SDP in the INVITE. Offer in the reliable response. Answer in the ACK.", "href": "rooms/T05-pitfalls-6337.html", "room": "Offer/answer pitfalls in RFC 6337" }, { "front": "Do not rebuild", "back": "Edit m-lines in place. Do not drop, swap, or renumber them.", "href": "rooms/T05-pitfalls-6337.html", "room": "Offer/answer pitfalls in RFC 6337" }, { "front": "V=2", "back": "RTP version is 2.", "href": "rooms/T06-rtp-header.html", "room": "The RTP header" }, { "front": "Sequence", "back": "Plus one for every packet from that source.", "href": "rooms/T06-rtp-header.html", "room": "The RTP header" }, { "front": "Timestamp", "back": "Media clock. 20 ms of G.711 or G.722 steps by 160.", "href": "rooms/T06-rtp-header.html", "room": "The RTP header" }, { "front": "SSRC", "back": "32-bit source id chosen by the sender.", "href": "rooms/T06-rtp-header.html", "room": "The RTP header" }, { "front": "PT 0", "back": "PCMU/8000, static.", "href": "rooms/T06-payload-types.html", "room": "Static and dynamic payload types" }, { "front": "PT 8", "back": "PCMA/8000, static. Not the same as PCMU.", "href": "rooms/T06-payload-types.html", "room": "Static and dynamic payload types" }, { "front": "PT 9", "back": "G722/8000. Sample rate is still 16 kHz.", "href": "rooms/T06-payload-types.html", "room": "Static and dynamic payload types" }, { "front": "PT 18", "back": "G729/8000, static.", "href": "rooms/T06-payload-types.html", "room": "Static and dynamic payload types" }, { "front": "G.711", "back": "PCMU/8000 and PCMA/8000. Read ITU-T G.711. They are not interchangeable.", "href": "rooms/T06-codec-choices.html", "room": "G.711, G.729, and Opus" }, { "front": "G.729", "back": "rtpmap G729/8000, static PT 18. Read ITU-T G.729. This course states no licensing result.", "href": "rooms/T06-codec-choices.html", "room": "G.711, G.729, and Opus" }, { "front": "Opus", "back": "RFC 6716. Read the RFC and the license.", "href": "rooms/T06-codec-choices.html", "room": "G.711, G.729, and Opus" }, { "front": "IPR", "back": "Check IETF IPR disclosures. This course states no legal result.", "href": "rooms/T06-codec-choices.html", "room": "G.711, G.729, and Opus" }, { "front": "SR", "back": "Sender report. Used when this participant has sent RTP.", "href": "rooms/T06-rtcp.html", "room": "RTCP sender and receiver reports" }, { "front": "RR", "back": "Receiver report. Fraction lost, cumulative loss, jitter.", "href": "rooms/T06-rtcp.html", "room": "RTCP sender and receiver reports" }, { "front": "Port pair", "back": "RTP on an even port, RTCP on the next higher port, by default.", "href": "rooms/T06-rtcp.html", "room": "RTCP sender and receiver reports" }, { "front": "Not SIP", "back": "200 OK does not carry fraction lost.", "href": "rooms/T06-rtcp.html", "room": "RTCP sender and receiver reports" }, { "front": "RFC 4733", "back": "telephone-event. Obsoletes RFC 2833. Trust the status banner.", "href": "rooms/T06-telephone-event.html", "room": "telephone-event and other digit paths" }, { "front": "Events 0-15", "back": "DTMF. Event 16 is flash.", "href": "rooms/T06-telephone-event.html", "room": "telephone-event and other digit paths" }, { "front": "Dynamic PT", "back": "Match the name telephone-event in SDP.", "href": "rooms/T06-telephone-event.html", "room": "telephone-event and other digit paths" }, { "front": "Not INFO", "back": "RFC 6086 is a method. application/dtmf-relay is a vendor body.", "href": "rooms/T06-telephone-event.html", "room": "telephone-event and other digit paths" }, { "front": "a=ptime:20", "back": "20 ms of media per packet. SDP, not RTP.", "href": "rooms/T06-ptime.html", "room": "ptime, packet rate, and EF" }, { "front": "50 and 160", "back": "G.711 at 20 ms: 50 packets/s, 160 payload bytes, plus headers.", "href": "rooms/T06-ptime.html", "room": "ptime, packet rate, and EF" }, { "front": "EF", "back": "Voice service class in RFC 4594.", "href": "rooms/T06-ptime.html", "room": "ptime, packet rate, and EF" }, { "front": "RFC 3246", "back": "Defines the EF per-hop behavior. No router config in this lesson.", "href": "rooms/T06-ptime.html", "room": "ptime, packet rate, and EF" }, { "front": "200 OK", "back": "Offer/answer finished. It does not prove both RTP directions.", "href": "rooms/T06-one-way-audio.html", "room": "One-way audio" }, { "front": "sendonly answer", "back": "Answerer sends, does not receive. One-way by negotiation.", "href": "rooms/T06-one-way-audio.html", "room": "One-way audio" }, { "front": "c= and port", "back": "The destination you must capture.", "href": "rooms/T06-one-way-audio.html", "room": "One-way audio" }, { "front": "SR from one side", "back": "The other side is not sending, according to RTCP.", "href": "rooms/T06-one-way-audio.html", "room": "One-way audio" }, { "front": "401", "back": "From the UAS. Challenge is WWW-Authenticate. Retry with Authorization.", "href": "rooms/T07-digest.html", "room": "401, 407, and digest" }, { "front": "407", "back": "From the proxy. Challenge is Proxy-Authenticate. Retry with Proxy-Authorization.", "href": "rooms/T07-digest.html", "room": "401, 407, and digest" }, { "front": "RFC 7616", "back": "HTTP digest algorithms. Read the algorithm parameter.", "href": "rooms/T07-digest.html", "room": "401, 407, and digest" }, { "front": "Stop here", "back": "Identify the header. Do not compute a digest in this lesson.", "href": "rooms/T07-digest.html", "room": "401, 407, and digest" }, { "front": "RFC 3261 §18", "back": "SIP over TLS. Same methods. Via transport TLS.", "href": "rooms/T07-tls-certs.html", "room": "TLS and domain certificates" }, { "front": "5061", "back": "Usual TLS port in RFC 3261.", "href": "rooms/T07-tls-certs.html", "room": "TLS and domain certificates" }, { "front": "RFC 5922", "back": "The certificate must identify the SIP domain.", "href": "rooms/T07-tls-certs.html", "room": "TLS and domain certificates" }, { "front": "Not SRTP", "back": "TLS on SIP does not select the media keying method.", "href": "rooms/T07-tls-certs.html", "room": "TLS and domain certificates" }, { "front": "RFC 3711", "back": "SRTP. Protects RTP. Profile RTP/SAVP.", "href": "rooms/T07-srtp-keying.html", "room": "SRTP and two keying methods" }, { "front": "RFC 4568", "back": "SDES. a=crypto in SDP. Protect the signaling.", "href": "rooms/T07-srtp-keying.html", "room": "SRTP and two keying methods" }, { "front": "RFC 5764", "back": "DTLS-SRTP. Keys from DTLS. Fingerprint in SDP.", "href": "rooms/T07-srtp-keying.html", "room": "SRTP and two keying methods" }, { "front": "Per leg", "back": "Do not assume two peers share one keying method.", "href": "rooms/T07-srtp-keying.html", "room": "SRTP and two keying methods" }, { "front": "RFC 3323", "back": "Privacy header. id withholds a network-asserted identity.", "href": "rooms/T07-privacy-pai.html", "room": "Privacy and asserted identity" }, { "front": "PPI", "back": "P-Preferred-Identity. A hint from the UA inside the trust domain.", "href": "rooms/T07-privacy-pai.html", "room": "Privacy and asserted identity" }, { "front": "PAI", "back": "P-Asserted-Identity. Trusted networks only. Not a signature.", "href": "rooms/T07-privacy-pai.html", "room": "Privacy and asserted identity" }, { "front": "Strip", "back": "Remove PAI and PPI when the request leaves the trust domain.", "href": "rooms/T07-privacy-pai.html", "room": "Privacy and asserted identity" }, { "front": "RFC 8224", "back": "STIR. Identity header in SIP.", "href": "rooms/T07-stir-shaken.html", "room": "STIR, PASSporT, and SHAKEN" }, { "front": "RFC 8225", "back": "PASSporT.", "href": "rooms/T07-stir-shaken.html", "room": "STIR, PASSporT, and SHAKEN" }, { "front": "RFC 8226", "back": "Certificates for STIR.", "href": "rooms/T07-stir-shaken.html", "room": "STIR, PASSporT, and SHAKEN" }, { "front": "Levels A/B/C", "back": "ATIS SHAKEN. Confirm the current ATIS document. See also the FCC page.", "href": "rooms/T07-stir-shaken.html", "room": "STIR, PASSporT, and SHAKEN" }, { "front": "Scanning", "back": "Unsolicited SIP from addresses you did not provision. Close the exposure.", "href": "rooms/T07-threats.html", "room": "Scanning, hijack, and toll fraud" }, { "front": "Hijack", "back": "Unexpected Contact on an address-of-record. Authenticate REGISTER.", "href": "rooms/T07-threats.html", "room": "Scanning, hijack, and toll fraud" }, { "front": "Toll fraud", "back": "Unauthorized calls that run up charges. Authorize the source.", "href": "rooms/T07-threats.html", "room": "Scanning, hijack, and toll fraud" }, { "front": "FCC page", "back": "Call authentication is not a substitute for outbound authorization.", "href": "rooms/T07-threats.html", "room": "Scanning, hijack, and toll fraud" }, { "front": "Allow list", "back": "Named peers only. See the CME toll-fraud guide for trusted sources.", "href": "rooms/T07-hardening.html", "room": "Hardening a SIP edge" }, { "front": "Digest", "back": "401 uses Authorization. 407 uses Proxy-Authorization.", "href": "rooms/T07-hardening.html", "room": "Hardening a SIP edge" }, { "front": "RFC 5922", "back": "Certificate name equals the SIP domain.", "href": "rooms/T07-hardening.html", "room": "Hardening a SIP edge" }, { "front": "Per-leg SRTP", "back": "Do not copy keying from one peer to another.", "href": "rooms/T07-hardening.html", "room": "Hardening a SIP edge" }, { "front": "Embedded", "back": "Via, Contact, and SDP c= carry addresses NAT does not rewrite.", "href": "rooms/T08-nat-breaks-sip.html", "room": "Embedded addresses and NAT" }, { "front": "c=", "back": "Media destination. A private value is non-routable on the public Internet.", "href": "rooms/T08-nat-breaks-sip.html", "room": "Embedded addresses and NAT" }, { "front": "200 OK", "back": "Signaling can succeed while RTP still cannot go where c= points.", "href": "rooms/T08-nat-breaks-sip.html", "room": "Embedded addresses and NAT" }, { "front": "RFC 5737", "back": "203.0.113.10 and the other lab addresses are documentation ranges.", "href": "rooms/T08-nat-breaks-sip.html", "room": "Embedded addresses and NAT" }, { "front": "RFC 3581", "back": "rport. Symmetric SIP response routing.", "href": "rooms/T08-rport.html", "room": "rport and symmetric responses" }, { "front": "received", "back": "Source address the server saw.", "href": "rooms/T08-rport.html", "room": "rport and symmetric responses" }, { "front": "rport value", "back": "Source port the server saw.", "href": "rooms/T08-rport.html", "room": "rport and symmetric responses" }, { "front": "Not SDP", "back": "rport does not rewrite c=.", "href": "rooms/T08-rport.html", "room": "rport and symmetric responses" }, { "front": "RFC 8489", "back": "Current STUN. Obsoletes RFC 5389. Trust the status banner.", "href": "rooms/T08-stun.html", "room": "STUN server-reflexive addresses" }, { "front": "Binding", "back": "Request that asks what address the server sees.", "href": "rooms/T08-stun.html", "room": "STUN server-reflexive addresses" }, { "front": "XOR-MAPPED-ADDRESS", "back": "The reflexive address in the success response.", "href": "rooms/T08-stun.html", "room": "STUN server-reflexive addresses" }, { "front": "Not SIP", "back": "A STUN server does not store a SIP Contact.", "href": "rooms/T08-stun.html", "room": "STUN server-reflexive addresses" }, { "front": "RFC 8656", "back": "Current TURN. Obsoletes RFC 5766. Trust the status banner.", "href": "rooms/T08-turn.html", "room": "TURN relays" }, { "front": "Allocate", "back": "Reserves a relayed transport address.", "href": "rooms/T08-turn.html", "room": "TURN relays" }, { "front": "Relay", "back": "Peers send media to the relay. TURN forwards it.", "href": "rooms/T08-turn.html", "room": "TURN relays" }, { "front": "Not SIP", "back": "Allocate is not REGISTER and not an SDP rewrite.", "href": "rooms/T08-turn.html", "room": "TURN relays" }, { "front": "RFC 8445", "back": "Current ICE. Obsoletes RFC 5245. Trust the status banner.", "href": "rooms/T08-ice.html", "room": "ICE candidate types" }, { "front": "host", "back": "Local interface.", "href": "rooms/T08-ice.html", "room": "ICE candidate types" }, { "front": "srflx / relay", "back": "STUN reflexive address, and TURN relay.", "href": "rooms/T08-ice.html", "room": "ICE candidate types" }, { "front": "prflx", "back": "Discovered during a connectivity check.", "href": "rooms/T08-ice.html", "room": "ICE candidate types" }, { "front": "ALG", "back": "In-path SIP and SDP rewrite. Often corrupts the call.", "href": "rooms/T08-sip-alg.html", "room": "The SIP ALG problem" }, { "front": "Length", "back": "If Content-Length does not match the body, the edit is corrupt.", "href": "rooms/T08-sip-alg.html", "room": "The SIP ALG problem" }, { "front": "TLS", "back": "The ALG cannot rewrite what it cannot see.", "href": "rooms/T08-sip-alg.html", "room": "The SIP ALG problem" }, { "front": "Disable it", "back": "Turn the ALG off. Do not stack a second hidden editor.", "href": "rooms/T08-sip-alg.html", "room": "The SIP ALG problem" }, { "front": "Latch", "back": "Learn the remote RTP address from the first packet instead of trusting c=.", "href": "rooms/T08-media-latching.html", "room": "Media latching on an SBC" }, { "front": "RFC 5853", "back": "SBC requirements. Not an IETF algorithm for latching.", "href": "rooms/T08-media-latching.html", "room": "Media latching on an SBC" }, { "front": "Authenticated", "back": "Latch only after signaling is accepted, and only toward the expected side.", "href": "rooms/T08-media-latching.html", "room": "Media latching on an SBC" }, { "front": "ICE", "back": "RFC 8445 is the specified candidate check when both ends use it.", "href": "rooms/T08-media-latching.html", "room": "Media latching on an SBC" }, { "front": "RFC 5853", "back": "Informational requirements from SBC deployments. Not an SBC protocol.", "href": "rooms/T09-requirements-5853.html", "room": "RFC 5853 is requirements, not a protocol" }, { "front": "No SBC method", "back": "INVITE and OPTIONS stay as RFC 3261 defined them.", "href": "rooms/T09-requirements-5853.html", "room": "RFC 5853 is requirements, not a protocol" }, { "front": "Datasheet", "back": "Session and transcode limits are platform-specific.", "href": "rooms/T09-requirements-5853.html", "room": "RFC 5853 is requirements, not a protocol" }, { "front": "B2BUA", "back": "The usual SIP role behind an SBC. Taxonomy is RFC 7092.", "href": "rooms/T09-requirements-5853.html", "room": "RFC 5853 is requirements, not a protocol" }, { "front": "B2BUA", "back": "UAS plus UAC. Two dialogs for one call.", "href": "rooms/T09-b2bua-7092.html", "room": "An SBC is commonly a B2BUA" }, { "front": "Pure proxy", "back": "Forwards the request and adds Via.", "href": "rooms/T09-b2bua-7092.html", "room": "An SBC is commonly a B2BUA" }, { "front": "Call-ID", "back": "Often different on the two legs of an SBC.", "href": "rooms/T09-b2bua-7092.html", "room": "An SBC is commonly a B2BUA" }, { "front": "RFC 3261", "back": "Defines the B2BUA as UAS concatenated with UAC.", "href": "rooms/T09-b2bua-7092.html", "room": "An SBC is commonly a B2BUA" }, { "front": "Via", "back": "Identifies the previous SIP hop. Hide the internal one.", "href": "rooms/T09-topology-hiding.html", "room": "Topology hiding rewrites the addresses you leak" }, { "front": "Contact", "back": "Dialog target. An SBC usually substitutes its own.", "href": "rooms/T09-topology-hiding.html", "room": "Topology hiding rewrites the addresses you leak" }, { "front": "c=", "back": "SDP connection address. Anchoring rewrites it.", "href": "rooms/T09-topology-hiding.html", "room": "Topology hiding rewrites the addresses you leak" }, { "front": "User-Agent", "back": "A common topology leak. Stripping it is a product rule.", "href": "rooms/T09-topology-hiding.html", "room": "Topology hiding rewrites the addresses you leak" }, { "front": "Anchor", "back": "RTP terminates on the SBC. SDP c= names the SBC.", "href": "rooms/T09-media-modes.html", "room": "Anchor, bypass, transcode, and DTMF" }, { "front": "Bypass", "back": "SIP through the SBC. Media between endpoints.", "href": "rooms/T09-media-modes.html", "room": "Anchor, bypass, transcode, and DTMF" }, { "front": "Transcode", "back": "Decode and encode. Capacity is on the datasheet.", "href": "rooms/T09-media-modes.html", "room": "Anchor, bypass, transcode, and DTMF" }, { "front": "telephone-event", "back": "RFC 4733 DTMF in RTP.", "href": "rooms/T09-media-modes.html", "room": "Anchor, bypass, transcode, and DTMF" }, { "front": "OPTIONS", "back": "Capability and liveness request. RFC 3261.", "href": "rooms/T09-options-keepalive.html", "room": "OPTIONS keepalives" }, { "front": "CSeq method", "back": "Must match the start line. OPTIONS stays OPTIONS.", "href": "rooms/T09-options-keepalive.html", "room": "OPTIONS keepalives" }, { "front": "200 OK", "back": "The peer answered. The call is a later transaction.", "href": "rooms/T09-options-keepalive.html", "room": "OPTIONS keepalives" }, { "front": "Interval", "back": "Configured on the product. Not an RFC constant.", "href": "rooms/T09-options-keepalive.html", "room": "OPTIONS keepalives" }, { "front": "Admission", "back": "Refuse new work when the configured budget is exhausted.", "href": "rooms/T09-admission.html", "room": "Call admission stays on the datasheet" }, { "front": "503", "back": "Service Unavailable. Confirm the product’s actual code.", "href": "rooms/T09-admission.html", "room": "Call admission stays on the datasheet" }, { "front": "Datasheet", "back": "The only source for this platform’s session limit.", "href": "rooms/T09-admission.html", "room": "Call admission stays on the datasheet" }, { "front": "No CPS formula", "back": "Do not invent calls-per-second math.", "href": "rooms/T09-admission.html", "room": "Call admission stays on the datasheet" }, { "front": "Active", "back": "The unit currently processing the dialogs.", "href": "rooms/T09-high-availability.html", "room": "Active and standby, without a made-up timer" }, { "front": "Standby", "back": "Ready to take the role. Not a SIP method.", "href": "rooms/T09-high-availability.html", "room": "Active and standby, without a made-up timer" }, { "front": "No timer here", "back": "Do not invent a failover interval.", "href": "rooms/T09-high-availability.html", "room": "Active and standby, without a made-up timer" }, { "front": "Dialog state", "back": "A B2BUA holds it. Survival is a product question.", "href": "rooms/T09-high-availability.html", "room": "Active and standby, without a made-up timer" }, { "front": "CUBE", "back": "Cisco Unified Border Element. An IOS XE B2BUA.", "href": "rooms/T10-cube-role.html", "room": "CUBE is an IOS XE B2BUA" }, { "front": "IOS XE", "back": "The operating system whose voice stack CUBE uses.", "href": "rooms/T10-cube-role.html", "room": "CUBE is an IOS XE B2BUA" }, { "front": "SIP profiles", "back": "Header modifications. Guide for 17.6 and later.", "href": "rooms/T10-cube-role.html", "room": "CUBE is an IOS XE B2BUA" }, { "front": "B2BUA", "back": "The role RFC 7092 taxonomizes.", "href": "rooms/T10-cube-role.html", "room": "CUBE is an IOS XE B2BUA" }, { "front": "dial-peer voice N voip", "back": "Creates the VoIP dial peer numbered N.", "href": "rooms/T10-dial-peers.html", "room": "Dial peers select the SIP next hop" }, { "front": "session protocol sipv2", "back": "This dial peer speaks SIP.", "href": "rooms/T10-dial-peers.html", "room": "Dial peers select the SIP next hop" }, { "front": "session target ipv4:", "back": "The next-hop IPv4 address.", "href": "rooms/T10-dial-peers.html", "room": "Dial peers select the SIP next hop" }, { "front": "192.0.2.40", "back": "Carrier address in this synthetic.", "href": "rooms/T10-dial-peers.html", "room": "Dial peers select the SIP next hop" }, { "front": "sip-profiles", "back": "voice class sip-profiles N holds the rules.", "href": "rooms/T10-sip-profiles.html", "room": "voice class sip-profiles" }, { "front": "remove", "back": "request INVITE sip-header Diversion remove.", "href": "rooms/T10-sip-profiles.html", "room": "voice class sip-profiles" }, { "front": "After 15.4", "back": "Inbound profile support, per the use-case technote.", "href": "rooms/T10-sip-profiles.html", "room": "voice class sip-profiles" }, { "front": "CSA tester", "back": "Try the profile before loading it.", "href": "rooms/T10-sip-profiles.html", "room": "voice class sip-profiles" }, { "front": "Delayed offer", "back": "INVITE without SDP. Offer comes later.", "href": "rooms/T10-early-delayed.html", "room": "Early offer and delayed offer" }, { "front": "Early offer", "back": "The INVITE already contains the offer.", "href": "rooms/T10-early-delayed.html", "room": "Early offer and delayed offer" }, { "front": "early-offer forced", "back": "Dial-peer command that forces an outbound offer.", "href": "rooms/T10-early-delayed.html", "room": "Early offer and delayed offer" }, { "front": "ACK answer", "back": "Used when the offer arrived in the 200 OK.", "href": "rooms/T10-early-delayed.html", "room": "Early offer and delayed offer" }, { "front": "SIP trunk", "back": "CUCM’s adjacency to CUBE or another peer.", "href": "rooms/T10-cucm-trunk.html", "room": "CUCM trunks, SIP profiles, and Lua" }, { "front": "CUCM SIP profile", "back": "Not voice class sip-profiles.", "href": "rooms/T10-cucm-trunk.html", "room": "CUCM trunks, SIP profiles, and Lua" }, { "front": "Lua", "back": "Normalization scripts exist. Open the admin guide.", "href": "rooms/T10-cucm-trunk.html", "room": "CUCM trunks, SIP profiles, and Lua" }, { "front": "MTP required", "back": "Confirm the guide for that version before checking it.", "href": "rooms/T10-cucm-trunk.html", "room": "CUCM trunks, SIP profiles, and Lua" }, { "front": "SIP integration", "back": "The documented Unity Connection path. Open your version’s guide.", "href": "rooms/T10-unity.html", "room": "Unity Connection SIP integration" }, { "front": "Diversion", "back": "RFC 5806 redirecting number. Reason unconditional in the lab.", "href": "rooms/T10-unity.html", "room": "Unity Connection SIP integration" }, { "front": "History-Info", "back": "RFC 7044. Use it if the guide asks for it.", "href": "rooms/T10-unity.html", "room": "Unity Connection SIP integration" }, { "front": "Not SCCP-by-guess", "back": "Do not invent SCCP as the current default.", "href": "rooms/T10-unity.html", "room": "Unity Connection SIP integration" }, { "front": "debug ccsip messages", "back": "Shows sent and received SIP.", "href": "rooms/T10-debug-ccsip.html", "room": "debug ccsip messages" }, { "front": "sip-profiles debug", "back": "debug ccsip feature sip-profiles.", "href": "rooms/T10-debug-ccsip.html", "room": "debug ccsip messages" }, { "front": "CSA", "back": "SIP Profile Tester in Collaboration Solutions Analyzer.", "href": "rooms/T10-debug-ccsip.html", "room": "debug ccsip messages" }, { "front": "Sent / Received", "back": "Direction markers around each SIP message.", "href": "rooms/T10-debug-ccsip.html", "room": "debug ccsip messages" }, { "front": "realm", "back": "Routing and policy context on the Oracle SBC.", "href": "rooms/T11-oracle-objects.html", "room": "Oracle SBC objects" }, { "front": "session-agent", "back": "Named next hop.", "href": "rooms/T11-oracle-objects.html", "room": "Oracle SBC objects" }, { "front": "in-manipulationid", "back": "Which sip-manipulation runs on arrival.", "href": "rooms/T11-oracle-objects.html", "room": "Oracle SBC objects" }, { "front": "out-manipulationid", "back": "Which sip-manipulation runs on the way out.", "href": "rooms/T11-oracle-objects.html", "room": "Oracle SBC objects" }, { "front": "header-rule", "back": "One rule inside a sip-manipulation.", "href": "rooms/T11-acme-hmr.html", "room": "Header rules run in order" }, { "front": "delete", "back": "Removes the named header. Lab rule strip-server.", "href": "rooms/T11-acme-hmr.html", "room": "Header rules run in order" }, { "front": "store", "back": "Keeps a value for a later rule. Run it first.", "href": "rooms/T11-acme-hmr.html", "room": "Header rules run in order" }, { "front": "reject", "back": "An HMR action. Read the release guide for the status.", "href": "rooms/T11-acme-hmr.html", "room": "Header rules run in order" }, { "front": "SWe Edge", "back": "Edge product. Family includes SBC 1000 and SBC 2000.", "href": "rooms/T11-ribbon-families.html", "room": "Ribbon Edge, Core, and public validation lists" }, { "front": "SBC Core", "back": "A separate family.", "href": "rooms/T11-ribbon-families.html", "room": "Ribbon Edge, Core, and public validation lists" }, { "front": "ACS snapshot", "back": "5110, 5210, 5400, 7000, and SWe for that validation.", "href": "rooms/T11-ribbon-families.html", "room": "Ribbon Edge, Core, and public validation lists" }, { "front": "No invented CLI", "back": "Admin guides live on the documentation portal.", "href": "rooms/T11-ribbon-families.html", "room": "Ribbon Edge, Core, and public validation lists" }, { "front": "Action Subject", "back": "Which header or element the rule touches.", "href": "rooms/T11-audiocodes-rules.html", "room": "AudioCodes manipulation in software 7.6" }, { "front": "Action Type", "back": "Add, Remove, Modify, prefix, suffix, or Normalize.", "href": "rooms/T11-audiocodes-rules.html", "room": "AudioCodes manipulation in software 7.6" }, { "front": "IP group", "back": "Inbound or outbound assignment of the set.", "href": "rooms/T11-audiocodes-rules.html", "room": "AudioCodes manipulation in software 7.6" }, { "front": "Release menu", "back": "The clicks change. Use the 7.6 manual you are running.", "href": "rooms/T11-audiocodes-rules.html", "room": "AudioCodes manipulation in software 7.6" }, { "front": "CUBE line", "back": "request INVITE sip-header NAME remove.", "href": "rooms/T11-compare-manipulation.html", "room": "Three manipulation grammars" }, { "front": "Oracle block", "back": "header-rule, header-name, action delete.", "href": "rooms/T11-compare-manipulation.html", "room": "Three manipulation grammars" }, { "front": "AudioCodes row", "back": "Action Type Remove on an IP group.", "href": "rooms/T11-compare-manipulation.html", "room": "Three manipulation grammars" }, { "front": "Do not paste across", "back": "Each grammar is parsed by its own product.", "href": "rooms/T11-compare-manipulation.html", "room": "Three manipulation grammars" }, { "front": "PAI", "back": "P-Asserted-Identity, RFC 3325.", "href": "rooms/T11-pai-interop.html", "room": "Identity at a trust boundary" }, { "front": "Privacy", "back": "RFC 3323. id asks the network to withhold identity.", "href": "rooms/T11-pai-interop.html", "room": "Identity at a trust boundary" }, { "front": "Diversion", "back": "RFC 5806 redirecting header.", "href": "rooms/T11-pai-interop.html", "room": "Identity at a trust boundary" }, { "front": "History-Info", "back": "RFC 7044. Map it only as the interop guide says.", "href": "rooms/T11-pai-interop.html", "room": "Identity at a trust boundary" }, { "front": "RFC 5922", "back": "SIP domain certificates.", "href": "rooms/T11-certificate-fqdn.html", "room": "Certificate names and Contact" }, { "front": "Teams Contact", "back": "FQDN. An IP draws 403.", "href": "rooms/T11-certificate-fqdn.html", "room": "Certificate names and Contact" }, { "front": "Teams wildcard", "back": "CN or SAN wildcards are supported for Direct Routing.", "href": "rooms/T11-certificate-fqdn.html", "room": "Certificate names and Contact" }, { "front": "Webex LGW wildcard", "back": "Not supported for Local Gateway.", "href": "rooms/T11-certificate-fqdn.html", "room": "Certificate names and Contact" }, { "front": "pstnhub", "back": "sip, sip2, and sip3.pstnhub.microsoft.com.", "href": "rooms/T12-teams-signaling.html", "room": "Teams Direct Routing signaling" }, { "front": "5061", "back": "Direct Routing signaling port.", "href": "rooms/T12-teams-signaling.html", "room": "Teams Direct Routing signaling" }, { "front": "Verified domain", "back": "Not a name ending in onmicrosoft.com.", "href": "rooms/T12-teams-signaling.html", "room": "Teams Direct Routing signaling" }, { "front": "No RFC 5923", "back": "The SIP proxy does not support connection aliasing.", "href": "rooms/T12-teams-signaling.html", "room": "Teams Direct Routing signaling" }, { "front": "OPTIONS 200", "back": "Marks the Direct Routing SBC healthy.", "href": "rooms/T12-teams-options-media.html", "room": "OPTIONS health and SRTP media" }, { "front": "CSeq", "back": "Method token matches the request. OPTIONS, not INVITE.", "href": "rooms/T12-teams-options-media.html", "room": "OPTIONS health and SRTP media" }, { "front": "Table cell", "back": "Checked 2026-10-14: CSeq: 1 INVITE. Do not copy it.", "href": "rooms/T12-teams-options-media.html", "room": "OPTIONS health and SRTP media" }, { "front": "SRTP", "back": "Media processors use SRTP. RFC 3711.", "href": "rooms/T12-teams-options-media.html", "room": "OPTIONS health and SRTP media" }, { "front": "SIP TLS", "back": "Signaling from an IOS XE Local Gateway to Webex.", "href": "rooms/T12-webex-lgw.html", "room": "Webex Calling Local Gateway" }, { "front": "SRTP", "back": "Media for that IOS XE Local Gateway.", "href": "rooms/T12-webex-lgw.html", "room": "Webex Calling Local Gateway" }, { "front": "Certificate trunk", "back": "How a third-party SBC is supported.", "href": "rooms/T12-webex-lgw.html", "room": "Webex Calling Local Gateway" }, { "front": "ByoPSTN", "back": "Bring your own PSTN. Not Cloud Connected PSTN.", "href": "rooms/T12-webex-lgw.html", "room": "Webex Calling Local Gateway" }, { "front": "Cisco Calling Plan", "back": "One of the three organization-article choices.", "href": "rooms/T12-webex-pstn-models.html", "room": "Three PSTN choices, one per location" }, { "front": "Cloud Connected PSTN", "back": "A cloud partner through Webex. Not the Local Gateway.", "href": "rooms/T12-webex-pstn-models.html", "room": "Three PSTN choices, one per location" }, { "front": "Local Gateway", "back": "Premises-based PSTN. One connection on the location.", "href": "rooms/T12-webex-pstn-models.html", "room": "Three PSTN choices, one per location" }, { "front": "ByoPSTN", "back": "Bring your own PSTN.", "href": "rooms/T12-webex-pstn-models.html", "room": "Three PSTN choices, one per location" }, { "front": "Managed PSTN", "back": "Ordinary Connect calls. No customer SIP trunk required.", "href": "rooms/T12-connect-boundaries.html", "room": "Amazon Connect voice boundaries" }, { "front": "SIPREC", "back": "External voice into the analytics connector.", "href": "rooms/T12-connect-boundaries.html", "room": "Amazon Connect voice boundaries" }, { "front": "Voice Connector", "back": "Chime SDK SIP trunking service.", "href": "rooms/T12-connect-boundaries.html", "room": "Amazon Connect voice boundaries" }, { "front": "Not a bridge", "back": "Carrier through Voice Connector into Connect needs specialist approval.", "href": "rooms/T12-connect-boundaries.html", "room": "Amazon Connect voice boundaries" }, { "front": "BYO SIP", "back": "Your ITSP or gateway connects to Five9 SBCs.", "href": "rooms/T12-five9-twilio.html", "room": "Five9 BYO SIP and Twilio trunks" }, { "front": "Entitled groups", "back": "Self-service exists for entitled BYO SIP trunk groups.", "href": "rooms/T12-five9-twilio.html", "room": "Five9 BYO SIP and Twilio trunks" }, { "front": "Termination URI", "back": "Must appear in the Request-URI or Twilio drops the request.", "href": "rooms/T12-five9-twilio.html", "room": "Five9 BYO SIP and Twilio trunks" }, { "front": "sip not sips", "back": "Origination URLs use sip. sips is not supported.", "href": "rooms/T12-five9-twilio.html", "room": "Five9 BYO SIP and Twilio trunks" }, { "front": "BYOC Cloud", "back": "Public internet SIP. RTP crosses the internet.", "href": "rooms/T12-genesys-cxone.html", "room": "Genesys BYOC and NICE CXone SIP" }, { "front": "BYOC Premises", "back": "Customer-managed Edge. Hybrid media is allowed.", "href": "rooms/T12-genesys-cxone.html", "room": "Genesys BYOC and NICE CXone SIP" }, { "front": "December 1, 2026", "back": "Genesys Hardware Solution only.", "href": "rooms/T12-genesys-cxone.html", "room": "Genesys BYOC and NICE CXone SIP" }, { "front": "CXone ports", "back": "5060 and 5061, plus dynamic RTP/SRTP.", "href": "rooms/T12-genesys-cxone.html", "room": "Genesys BYOC and NICE CXone SIP" }, { "front": "Call-ID", "back": "Same value for the dialog. A B2BUA may use a new one on the other leg.", "href": "rooms/T13-read-a-ladder.html", "room": "Match a ladder before you change anything" }, { "front": "CSeq", "back": "Integer plus method. The ACK for an INVITE keeps the INVITE's number.", "href": "rooms/T13-read-a-ladder.html", "room": "Match a ladder before you change anything" }, { "front": "Via branch", "back": "Transaction hop id. Look for the z9hG4bK cookie.", "href": "rooms/T13-read-a-ladder.html", "room": "Match a ladder before you change anything" }, { "front": "2xx ACK", "back": "End to end. New branch. RFC 6026 corrects the transaction rules around it.", "href": "rooms/T13-read-a-ladder.html", "room": "Match a ladder before you change anything" }, { "front": "180", "back": "Ringing. Provisional alerting.", "href": "rooms/T13-status-codes.html", "room": "Status codes you will actually see" }, { "front": "183", "back": "Session Progress. Provisional, often where early media shows up.", "href": "rooms/T13-status-codes.html", "room": "Status codes you will actually see" }, { "front": "487", "back": "Request Terminated. The INVITE's answer after CANCEL.", "href": "rooms/T13-status-codes.html", "room": "Status codes you will actually see" }, { "front": "606", "back": "Not Acceptable. Global. 488 is only this UA.", "href": "rooms/T13-status-codes.html", "room": "Status codes you will actually see" }, { "front": "sip", "back": "Display filter for SIP packets. Field names live on the SIP reference page.", "href": "rooms/T13-wireshark.html", "room": "Display filters for SIP and RTP" }, { "front": "rtp", "back": "Display filter for RTP packets. Field names live on the RTP reference page.", "href": "rooms/T13-wireshark.html", "room": "Display filters for SIP and RTP" }, { "front": "sip.Method", "back": "Safe display field for the SIP method.", "href": "rooms/T13-wireshark.html", "room": "Display filters for SIP and RTP" }, { "front": "Confirm CSeq", "back": "sip.CSeq.method is common. Confirm it on the SIP display-filter reference.", "href": "rooms/T13-wireshark.html", "room": "Display filters for SIP and RTP" }, { "front": "ccsip messages", "back": "IOS voice debug that prints SIP send and receive.", "href": "rooms/T13-ccsip-output.html", "room": "IOS ccsip and ccapi debug" }, { "front": "ccapi inout", "back": "IOS voice debug of the call-control API. Not a SIP RFC.", "href": "rooms/T13-ccsip-output.html", "room": "IOS ccsip and ccapi debug" }, { "front": "Sent / Received", "back": "Direction on the debug. The SIP start line comes after it.", "href": "rooms/T13-ccsip-output.html", "room": "IOS ccsip and ccapi debug" }, { "front": "Synthetic", "back": "Lab output in this track is synthetic. Customer logs stay out.", "href": "rooms/T13-ccsip-output.html", "room": "IOS ccsip and ccapi debug" }, { "front": "488", "back": "Not Acceptable Here. This UA. Often codec or SDP.", "href": "rooms/T13-codec-and-timer-failures.html", "room": "488 codecs and 422 session timers" }, { "front": "422", "back": "Session Interval Too Small. RFC 4028. Read Min-SE.", "href": "rooms/T13-codec-and-timer-failures.html", "room": "488 codecs and 422 session timers" }, { "front": "telephone-event", "back": "RFC 4733. Offer it on purpose if you need DTMF.", "href": "rooms/T13-codec-and-timer-failures.html", "room": "488 codecs and 422 session timers" }, { "front": "Offer/answer", "back": "The answer is a subset. No shared audio codec tends to 488.", "href": "rooms/T13-codec-and-timer-failures.html", "room": "488 codecs and 422 session timers" }, { "front": "Name mismatch", "back": "Handshake fails. No SIP status from the peer.", "href": "rooms/T13-tls-failures.html", "room": "TLS names, trust anchors, and version" }, { "front": "Untrusted CA", "back": "Handshake fails. Fix the trust anchor.", "href": "rooms/T13-tls-failures.html", "room": "TLS names, trust anchors, and version" }, { "front": "TLS 1.2+", "back": "Teams Direct Routing floor in the OPTIONS troubleshooting page.", "href": "rooms/T13-tls-failures.html", "room": "TLS names, trust anchors, and version" }, { "front": "FQDN Contact", "back": "Required toward Teams. An address literal draws 403.", "href": "rooms/T13-tls-failures.html", "room": "TLS names, trust anchors, and version" }, { "front": "Category", "back": "Read it on the header. 3261 is Standards Track. 6881 is BCP.", "href": "rooms/T13-build-a-timeline.html", "room": "Read an RFC header before you cite it" }, { "front": "Obsoletes", "back": "The new RFC names the one it replaces. 8866 and 4566 are the SDP pair here.", "href": "rooms/T13-build-a-timeline.html", "room": "Read an RFC header before you cite it" }, { "front": "Updates", "back": "A correction that leaves the base in force. Check 6026's header.", "href": "rooms/T13-build-a-timeline.html", "room": "Read an RFC header before you cite it" }, { "front": "rfc-editor.org", "back": "The header you cite. Months in this lesson are not invented.", "href": "rooms/T13-build-a-timeline.html", "room": "Read an RFC header before you cite it" }, { "front": "Trusted list", "back": "Who may present VoIP signaling. CME and SRST each have a page.", "href": "rooms/T14-fraud-class.html", "room": "The toll-fraud class, stated defensively" }, { "front": "401 / 407", "back": "UAS and proxy digest challenges. Secrets stay unprinted.", "href": "rooms/T14-fraud-class.html", "room": "The toll-fraud class, stated defensively" }, { "front": "Numbering plan", "back": "Dial-peers match the plan, including whether international destinations are in it.", "href": "rooms/T14-fraud-class.html", "room": "The toll-fraud class, stated defensively" }, { "front": "STIR context", "back": "FCC call authentication and RFC 8224. A different question from the source list.", "href": "rooms/T14-fraud-class.html", "room": "The toll-fraud class, stated defensively" }, { "front": "trusted list", "back": "Addresses allowed to present inbound VoIP. CME page or SRST page.", "href": "rooms/T14-trusted-list.html", "room": "Trusted addresses and source restrictions" }, { "front": "authenticate", "back": "The check that uses the list.", "href": "rooms/T14-trusted-list.html", "room": "Trusted addresses and source restrictions" }, { "front": "Two pages", "back": "CME and SRST differ. Quote no shared list size.", "href": "rooms/T14-trusted-list.html", "room": "Trusted addresses and source restrictions" }, { "front": "Border pair", "back": "198.51.100.30 and 192.0.2.40 in the teaching snippet.", "href": "rooms/T14-trusted-list.html", "room": "Trusted addresses and source restrictions" }, { "front": "urn:service:sos", "back": "RFC 5031 service URN for emergency calling.", "href": "rooms/T14-e911.html", "room": "Emergency calling, location, and the FCC page" }, { "front": "RFC 6881", "back": "BCP for emergency calling services.", "href": "rooms/T14-e911.html", "room": "Emergency calling, location, and the FCC page" }, { "front": "Geolocation", "back": "RFC 6442 location conveyance.", "href": "rooms/T14-e911.html", "room": "Emergency calling, location, and the FCC page" }, { "front": "fcc-mlts", "back": "Kari's Law and RAY BAUM's Act. The page wins over a retelling.", "href": "rooms/T14-e911.html", "room": "Emergency calling, location, and the FCC page" }, { "front": "7866", "back": "Session recording protocol. SRC forks to an SRS.", "href": "rooms/T14-siprec.html", "room": "Disclosed recording with SIPREC" }, { "front": "7865", "back": "Recording metadata. Read it for fields.", "href": "rooms/T14-siprec.html", "room": "Disclosed recording with SIPREC" }, { "front": "Disclosed", "back": "Quality monitoring and compliance, with the parties on notice.", "href": "rooms/T14-siprec.html", "room": "Disclosed recording with SIPREC" }, { "front": "Retention", "back": "A legal question. Outside the RFC.", "href": "rooms/T14-siprec.html", "room": "Disclosed recording with SIPREC" }, { "front": "EF", "back": "Expedited Forwarding per-hop behavior. RFC 3246.", "href": "rooms/T14-qos.html", "room": "Voice, EF, and what the PHB does not design" }, { "front": "Telephony", "back": "The service class RFC 4594 maps to EF.", "href": "rooms/T14-qos.html", "room": "Voice, EF, and what the PHB does not design" }, { "front": "Codepoint", "back": "Use the value RFC 3246 recommends. Do not invent a second one.", "href": "rooms/T14-qos.html", "room": "Voice, EF, and what the PHB does not design" }, { "front": "Not a LAN", "back": "Queues and campus policy stay in the approved design.", "href": "rooms/T14-qos.html", "room": "Voice, EF, and what the PHB does not design" }, { "front": "OPTIONS", "back": "Liveness. Alarm when the trunk stops answering.", "href": "rooms/T14-alarms.html", "room": "Alarms that match the failure" }, { "front": "503", "back": "Service Unavailable. Page the server-side class.", "href": "rooms/T14-alarms.html", "room": "Alarms that match the failure" }, { "front": "TLS floor", "back": "Toward Teams, 1.2 or newer, or the handshake never yields SIP.", "href": "rooms/T14-alarms.html", "room": "Alarms that match the failure" }, { "front": "SRS down", "back": "Recording-session alarm. RFC 7866. Retention stays outside the RFC.", "href": "rooms/T14-alarms.html", "room": "Alarms that match the failure" }, { "front": "Baseline", "back": "The last good OPTIONS or the current snippet, written down.", "href": "rooms/T14-change-window.html", "room": "One change in the window" }, { "front": "One variable", "back": "A single address, codec, or TLS setting.", "href": "rooms/T14-change-window.html", "room": "One change in the window" }, { "front": "Verify", "back": "One signal. A 200, or the test call to +15551212.", "href": "rooms/T14-change-window.html", "room": "One change in the window" }, { "front": "Rollback", "back": "The previous value of that same variable.", "href": "rooms/T14-change-window.html", "room": "One change in the window" }, { "front": "Role", "back": "What the box does on the ladder: UA, proxy, registrar, B2BUA.", "href": "rooms/T15-glossary-habit.html", "room": "A glossary tied to a document" }, { "front": "B2BUA", "back": "UAS plus UAC. RFC 7092. Typical SBC.", "href": "rooms/T15-glossary-habit.html", "room": "A glossary tied to a document" }, { "front": "Document", "back": "The cite you can open. A logo is not a document.", "href": "rooms/T15-glossary-habit.html", "room": "A glossary tied to a document" }, { "front": "SDP row", "back": "RFC 8866 now. RFC 4566 is the one it moved from.", "href": "rooms/T15-glossary-habit.html", "room": "A glossary tied to a document" }, { "front": "WFM / QM", "back": "Operations systems. No SIP RFC in this library.", "href": "rooms/T15-neighbors.html", "room": "Neighbors that are not SIP elements" }, { "front": "SIPREC", "back": "The recording neighbor that is SIP. RFC 7866 and RFC 7865.", "href": "rooms/T15-neighbors.html", "room": "Neighbors that are not SIP elements" }, { "front": "CRM", "back": "Not a SIP element. No invented vendor features.", "href": "rooms/T15-neighbors.html", "room": "Neighbors that are not SIP elements" }, { "front": "Above the media", "back": "Analytics and agents. SIP and RTP still carry the session.", "href": "rooms/T15-neighbors.html", "room": "Neighbors that are not SIP elements" }, { "front": "Above RTP", "back": "Analytics and agents. The packets remain RTP.", "href": "rooms/T15-workforce-and-ai.html", "room": "Workforce tools and agents above the media" }, { "front": "Dialog", "back": "Still Call-ID, CSeq, To tag. RFC 3261.", "href": "rooms/T15-workforce-and-ai.html", "room": "Workforce tools and agents above the media" }, { "front": "Disclosed fork", "back": "SIPREC when the SBC records. RFC 7866.", "href": "rooms/T15-workforce-and-ai.html", "room": "Workforce tools and agents above the media" }, { "front": "No invented features", "back": "Vendor guides or an honest gap. Not a fake RFC.", "href": "rooms/T15-workforce-and-ai.html", "room": "Workforce tools and agents above the media" }, { "front": "SSCA", "back": "SIP School Certified Associate. 20 CEC credits toward BICSI, per the SSCA page.", "href": "rooms/T15-certifications.html", "room": "Certifications this edition will name" }, { "front": "CLCOR", "back": "350-801. Core for CCNP Collaboration and the Collaboration Core specialist.", "href": "rooms/T15-certifications.html", "room": "Certifications this edition will name" }, { "front": "Concentrations", "back": "300-815 CLACC, 300-820 CLHCT, or 300-830 CLCCE. One of them, plus the core.", "href": "rooms/T15-certifications.html", "room": "Certifications this edition will name" }, { "front": "MS-721", "back": "Collaboration Communications Systems Engineer Associate. Certifications change. Use the link.", "href": "rooms/T15-certifications.html", "room": "Certifications this edition will name" }, { "front": "Banner", "back": "RFC Editor header beats a blog.", "href": "rooms/T15-reading-the-index.html", "room": "When the page and the memory disagree" }, { "front": "Cisco page", "back": "Exam topics change. The Cisco page wins.", "href": "rooms/T15-reading-the-index.html", "room": "When the page and the memory disagree" }, { "front": "MS-721 link", "back": "Certifications change. Use the certification page.", "href": "rooms/T15-reading-the-index.html", "room": "When the page and the memory disagree" }, { "front": "Checked dates", "back": "February 3, 2026. April 28, 2026. October 29, 2026. Source check 2026-10-14.", "href": "rooms/T15-reading-the-index.html", "room": "When the page and the memory disagree" }, { "front": "CUCM", "back": "Registrar and trunk call-control point.", "href": "rooms/T15-uc-bridge.html", "room": "CUCM, UCCX, and CVP without a fake script" }, { "front": "UCCX", "back": "Call control through CUCM. Not the carrier trunk.", "href": "rooms/T15-uc-bridge.html", "room": "CUCM, UCCX, and CVP without a fake script" }, { "front": "CUBE or CUCM", "back": "Where PSTN SIP lands.", "href": "rooms/T15-uc-bridge.html", "room": "CUCM, UCCX, and CVP without a fake script" }, { "front": "CVP", "back": "SIP among CVP, gateways, and CUCM, in that version's guide.", "href": "rooms/T15-uc-bridge.html", "room": "CUCM, UCCX, and CVP without a fake script" }, { "front": "Local Gateway", "back": "Premises PSTN pattern for Webex Calling.", "href": "rooms/T15-cloud-bridge.html", "room": "Webex Calling local gateway, and a separate contact center" }, { "front": "Organization PSTN", "back": "Configured on the Webex Calling PSTN page.", "href": "rooms/T15-cloud-bridge.html", "room": "Webex Calling local gateway, and a separate contact center" }, { "front": "Placeholder host", "back": "example.com stands in so the lesson does not invent the edge FQDN.", "href": "rooms/T15-cloud-bridge.html", "room": "Webex Calling local gateway, and a separate contact center" }, { "front": "Separate product", "back": "Webex Contact Center. Check its current design guide.", "href": "rooms/T15-cloud-bridge.html", "room": "Webex Calling local gateway, and a separate contact center" }, { "front": "Call-ID + To tag", "back": "Dialog match. No To tag on a brand-new INVITE.", "href": "rooms/T16-drill-signaling.html", "room": "Signaling drill with the cited answer" }, { "front": "Branch", "back": "Transaction hop. z9hG4bK.", "href": "rooms/T16-drill-signaling.html", "room": "Signaling drill with the cited answer" }, { "front": "2xx ACK", "back": "End to end. RFC 6026.", "href": "rooms/T16-drill-signaling.html", "room": "Signaling drill with the cited answer" }, { "front": "487", "back": "INVITE's final response after CANCEL. ACK is hop by hop.", "href": "rooms/T16-drill-signaling.html", "room": "Signaling drill with the cited answer" }, { "front": "488", "back": "This UA. Session description. RFC 3261 and RFC 3264.", "href": "rooms/T16-drill-media.html", "room": "Media drill with the cited answer" }, { "front": "422", "back": "RFC 4028. Raise the session interval to Min-SE.", "href": "rooms/T16-drill-media.html", "room": "Media drill with the cited answer" }, { "front": "telephone-event", "back": "RFC 4733. DTMF in the offer you mean.", "href": "rooms/T16-drill-media.html", "room": "Media drill with the cited answer" }, { "front": "Keying", "back": "RFC 3711 plus either RFC 4568 or RFC 5764. Record which.", "href": "rooms/T16-drill-media.html", "room": "Media drill with the cited answer" }, { "front": "RFC 7092", "back": "B2BUA taxonomy. New Call-ID on the other leg is normal.", "href": "rooms/T16-drill-sbc.html", "room": "SBC drill with the cited answer" }, { "front": "RFC 5853", "back": "SBC deployment requirements.", "href": "rooms/T16-drill-sbc.html", "room": "SBC drill with the cited answer" }, { "front": "Trunk landing", "back": "CUBE or CUCM. Not UCCX.", "href": "rooms/T16-drill-sbc.html", "room": "SBC drill with the cited answer" }, { "front": "Teams pair", "back": "TLS 1.2+ and an FQDN in Contact.", "href": "rooms/T16-drill-sbc.html", "room": "SBC drill with the cited answer" }, { "front": "Symptom", "back": "Silence after connect, Alice at 203.0.113.10. Written first.", "href": "rooms/T16-incident-method.html", "room": "Symptom, ladder, one packet, one variable" }, { "front": "Ladder", "back": "INVITE, 100, 180, 200, end-to-end ACK. One Call-ID.", "href": "rooms/T16-incident-method.html", "room": "Symptom, ladder, one packet, one variable" }, { "front": "One packet", "back": "200 OK SDP. 203.0.113.20, UDP 19642, PCMU.", "href": "rooms/T16-incident-method.html", "room": "Symptom, ladder, one packet, one variable" }, { "front": "One variable", "back": "Capture that port. Config edits wait, and then they are single.", "href": "rooms/T16-incident-method.html", "room": "Symptom, ladder, one packet, one variable" }, { "front": "Six rows", "back": "TLS, codecs, numbering, trusted addresses, OPTIONS, SRTP keying.", "href": "rooms/T16-design-interconnect.html", "room": "An interconnect checklist, not a config dump" }, { "front": "telephone-event", "back": "On the codec row on purpose. RFC 4733.", "href": "rooms/T16-design-interconnect.html", "room": "An interconnect checklist, not a config dump" }, { "front": "E.164", "back": "Number form. tel URI is RFC 3966.", "href": "rooms/T16-design-interconnect.html", "room": "An interconnect checklist, not a config dump" }, { "front": "Not a dump", "back": "Decisions only. No private key, no full dial-peer list.", "href": "rooms/T16-design-interconnect.html", "room": "An interconnect checklist, not a config dump" }, { "front": "Path", "back": "CUCM, then a certified SBC, then Teams. No invented SKU.", "href": "rooms/T16-design-teams-cucm.html", "room": "CUCM, a certified SBC, and Teams Direct Routing" }, { "front": "CUBE guide", "back": "Basic SIP configuration for the CUBE case.", "href": "rooms/T16-design-teams-cucm.html", "room": "CUCM, a certified SBC, and Teams Direct Routing" }, { "front": "TLS 1.2+", "back": "Teams floor. Handshake failures are not SIP codes.", "href": "rooms/T16-design-teams-cucm.html", "room": "CUCM, a certified SBC, and Teams Direct Routing" }, { "front": "FQDN Contact", "back": "sbc.example.com in the lab. An address literal draws 403.", "href": "rooms/T16-design-teams-cucm.html", "room": "CUCM, a certified SBC, and Teams Direct Routing" }, { "front": "SDP", "back": "RFC 4566 moved to RFC 8866.", "href": "rooms/T16-specs-move.html", "room": "When the RFC number moves" }, { "front": "ICE", "back": "RFC 5245 moved to RFC 8445. Confirm the banner.", "href": "rooms/T16-specs-move.html", "room": "When the RFC number moves" }, { "front": "STUN / TURN", "back": "RFC 8489 and RFC 8656 in this library. Predecessors 5389 and 5766.", "href": "rooms/T16-specs-move.html", "room": "When the RFC number moves" }, { "front": "Banner", "back": "A newer obsoleting RFC that this edition does not cite still wins.", "href": "rooms/T16-specs-move.html", "room": "When the RFC number moves" }, { "front": "RFC 8825", "back": "Applicability statement for WebRTC. It does not define SIP.", "href": "rooms/T17-signaling-planes.html", "room": "Signaling, JSEP, and the media plane" }, { "front": "JSEP", "back": "JavaScript controls signaling. SIP is one allowed choice.", "href": "rooms/T17-signaling-planes.html", "room": "Signaling, JSEP, and the media plane" }, { "front": "RFC 7118", "back": "WebSocket subprotocol sip for SIP messages.", "href": "rooms/T17-signaling-planes.html", "room": "Signaling, JSEP, and the media plane" }, { "front": "RFC 6455", "back": "WebSocket handshake and framing over TCP.", "href": "rooms/T17-signaling-planes.html", "room": "Signaling, JSEP, and the media plane" }, { "front": "sip", "back": "WebSocket subprotocol identifier for this transport.", "href": "rooms/T17-sip-websocket.html", "room": "RFC 7118: the sip subprotocol" }, { "front": "WSS", "back": "Via transport when the WebSocket used TLS.", "href": "rooms/T17-sip-websocket.html", "room": "RFC 7118: the sip subprotocol" }, { "front": "transport=ws", "back": "URI transport parameter added by RFC 7118.", "href": "rooms/T17-sip-websocket.html", "room": "RFC 7118: the sip subprotocol" }, { "front": "SIP+D2W", "back": "NAPTR service value for a SIP WebSocket server.", "href": "rooms/T17-sip-websocket.html", "room": "RFC 7118: the sip subprotocol" }, { "front": "3478", "back": "Default STUN port for UDP and TCP.", "href": "rooms/T17-ice-stun-turn.html", "room": "ICE, STUN, and TURN" }, { "front": "5349", "back": "Default port for STUN over TLS and DTLS.", "href": "rooms/T17-ice-stun-turn.html", "room": "ICE, STUN, and TURN" }, { "front": "Host / srflx / relay", "back": "Local interface, NAT mapping, TURN address.", "href": "rooms/T17-ice-stun-turn.html", "room": "ICE, STUN, and TURN" }, { "front": "TURN", "back": "A controlled relay. One address, multiple peers.", "href": "rooms/T17-ice-stun-turn.html", "room": "ICE, STUN, and TURN" }, { "front": "UDP/TLS/RTP/SAVPF", "back": "Proto token for SAVPF over DTLS with UDP.", "href": "rooms/T17-dtls-srtp-codecs.html", "room": "DTLS-SRTP and the required audio codecs" }, { "front": "use_srtp", "back": "DTLS extension type 14 for SRTP keying.", "href": "rooms/T17-dtls-srtp-codecs.html", "room": "DTLS-SRTP and the required audio codecs" }, { "front": "Opus clock", "back": "a=rtpmap clock 48000 and 2 channels.", "href": "rooms/T17-dtls-srtp-codecs.html", "room": "DTLS-SRTP and the required audio codecs" }, { "front": "PCMU and PCMA", "back": "Required G.711 codecs for WebRTC audio.", "href": "rooms/T17-dtls-srtp-codecs.html", "room": "DTLS-SRTP and the required audio codecs" }, { "front": "Step", "back": "Use the hop buttons. One caption at a time.", "href": "rooms/T17-browser-softphone.html", "room": "Browser softphone call flow" }, { "front": "101 then INVITE", "back": "Open the socket before the SIP request.", "href": "rooms/T17-browser-softphone.html", "room": "Browser softphone call flow" }, { "front": "ACK is not the key", "back": "SRTP keys come from DTLS, not from ACK.", "href": "rooms/T17-browser-softphone.html", "room": "Browser softphone call flow" }, { "front": "5737", "back": "Example addresses in this ladder are documentation ranges.", "href": "rooms/T17-browser-softphone.html", "room": "Browser softphone call flow" }, { "front": "Kamailio", "back": "SIP server. GPLv2+. Registrar, proxy, WebSocket.", "href": "rooms/T18-four-roles.html", "room": "Four projects, four roles" }, { "front": "rtpengine", "back": "RTP proxy for use with Kamailio. GNU/Linux.", "href": "rooms/T18-four-roles.html", "room": "Four projects, four roles" }, { "front": "Asterisk", "back": "Open source PBX. PJSIP lives in pjsip.conf.", "href": "rooms/T18-four-roles.html", "room": "Four projects, four roles" }, { "front": "FreeSWITCH", "back": "SIP profiles, dialplan, media, WebRTC, Event Socket.", "href": "rooms/T18-four-roles.html", "room": "Four projects, four roles" }, { "front": "pjsip.conf", "back": "Where res_pjsip accounts are written.", "href": "rooms/T18-asterisk-pjsip.html", "room": "Asterisk, PJSIP, and the dialplan" }, { "front": "extensions.conf", "back": "The dialplan file named in the overview.", "href": "rooms/T18-asterisk-pjsip.html", "room": "Asterisk, PJSIP, and the dialplan" }, { "front": "GPL version 2", "back": "The license page's stated distribution terms.", "href": "rooms/T18-asterisk-pjsip.html", "room": "Asterisk, PJSIP, and the dialplan" }, { "front": "ARI", "back": "Asterisk REST Interface, named next to AMI and AGI.", "href": "rooms/T18-asterisk-pjsip.html", "room": "Asterisk, PJSIP, and the dialplan" }, { "front": "SIP profile", "back": "Endpoint configuration the manual teaches.", "href": "rooms/T18-freeswitch-core.html", "room": "FreeSWITCH profiles, dialplan, and WebRTC" }, { "front": "Event Socket", "back": "Programming interface named in the manual.", "href": "rooms/T18-freeswitch-core.html", "room": "FreeSWITCH profiles, dialplan, and WebRTC" }, { "front": "Two editions", "back": "Open source, and enterprise from SignalWire.", "href": "rooms/T18-freeswitch-core.html", "room": "FreeSWITCH profiles, dialplan, and WebRTC" }, { "front": "SWML", "back": "Hosted call-control markup on the SignalWire page.", "href": "rooms/T18-freeswitch-core.html", "room": "FreeSWITCH profiles, dialplan, and WebRTC" }, { "front": "GPLv2+", "back": "The license the Kamailio home page states.", "href": "rooms/T18-kamailio-proxy.html", "room": "Kamailio as the SIP server" }, { "front": "Registrar", "back": "A role the page lists, with location service.", "href": "rooms/T18-kamailio-proxy.html", "room": "Kamailio as the SIP server" }, { "front": "WebSocket", "back": "Listed as support for WebRTC.", "href": "rooms/T18-kamailio-proxy.html", "room": "Kamailio as the SIP server" }, { "front": "In front of a PBX", "back": "The page names Asterisk and FreeSWITCH.", "href": "rooms/T18-kamailio-proxy.html", "room": "Kamailio as the SIP server" }, { "front": "With Kamailio", "back": "The README's intended SIP proxy.", "href": "rooms/T18-rtpengine-map.html", "room": "rtpengine and the integration map" }, { "front": "Userspace fallback", "back": "If the kernel module is unavailable.", "href": "rooms/T18-rtpengine-map.html", "room": "rtpengine and the integration map" }, { "front": "ICE bridge", "back": "Between ICE-aware and ICE-unaware agents.", "href": "rooms/T18-rtpengine-map.html", "room": "rtpengine and the integration map" }, { "front": "RTP and SRTP", "back": "The README lists a bridge between them.", "href": "rooms/T18-rtpengine-map.html", "room": "rtpengine and the integration map" }, { "front": "Not legal advice", "back": "Study notes. The statute and the agency page win.", "href": "rooms/T19-not-legal-advice.html", "room": "How to read a compliance page" }, { "front": "200 OK", "back": "SIP success. Not a compliance result.", "href": "rooms/T19-not-legal-advice.html", "room": "How to read a compliance page" }, { "front": "Confirm", "back": "No URL when the link was not opened.", "href": "rooms/T19-not-legal-advice.html", "room": "How to read a compliance page" }, { "front": "Separate planes", "back": "Voice identity, emergency location, and SMS campaigns are different documents.", "href": "rooms/T19-not-legal-advice.html", "room": "How to read a compliance page" }, { "front": "Identity", "back": "SIP header for the STIR signature. RFC 8224.", "href": "rooms/T19-stir-shaken.html", "room": "STIR and SHAKEN" }, { "front": "PASSporT", "back": "Signed token. RFC 8225.", "href": "rooms/T19-stir-shaken.html", "room": "STIR and SHAKEN" }, { "front": "SHAKEN", "back": "Industry mechanism described on the STI-GA page.", "href": "rooms/T19-stir-shaken.html", "room": "STIR and SHAKEN" }, { "front": "toKENs", "back": "The STI-GA page writes SHAKEN out with that word.", "href": "rooms/T19-stir-shaken.html", "room": "STIR and SHAKEN" }, { "front": "PL 115-127", "back": "Kari's Law. Direct 911 dialing from MLTS.", "href": "rooms/T19-e911-statutes.html", "room": "Kari's Law, RAY BAUM'S Act, and SIP location" }, { "front": "Section 506", "back": "Dispatchable location proceeding, including MLTS.", "href": "rooms/T19-e911-statutes.html", "room": "Kari's Law, RAY BAUM'S Act, and SIP location" }, { "front": "RFC 6442", "back": "How SIP conveys location.", "href": "rooms/T19-e911-statutes.html", "room": "Kari's Law, RAY BAUM'S Act, and SIP location" }, { "front": "RFC 6881", "back": "Emergency calling BCP. Not a statute.", "href": "rooms/T19-e911-statutes.html", "room": "Kari's Law, RAY BAUM'S Act, and SIP location" }, { "front": "10DLC", "back": "A2P messaging channel on the registry page.", "href": "rooms/T19-ten-dlc.html", "room": "10DLC is a messaging channel" }, { "front": "CSP", "back": "Campaign service provider. The page says to be one before registering.", "href": "rooms/T19-ten-dlc.html", "room": "10DLC is a messaging channel" }, { "front": "Campaign ID", "back": "Given to the connectivity partner, on that page.", "href": "rooms/T19-ten-dlc.html", "room": "10DLC is a messaging channel" }, { "front": "Not SIP", "back": "Do not add it to a voice INVITE and call it done.", "href": "rooms/T19-ten-dlc.html", "room": "10DLC is a messaging channel" }, { "front": "Sort first", "back": "SIP, media, identity, location, or messaging.", "href": "rooms/T19-compliance-troubleshoot.html", "room": "Troubleshooting without a legal conclusion" }, { "front": "No live 911", "back": "Use the provider test. This lab is not that test.", "href": "rooms/T19-compliance-troubleshoot.html", "room": "Troubleshooting without a legal conclusion" }, { "front": "Identity header", "back": "RFC 8224. Presence is not a legal conclusion.", "href": "rooms/T19-compliance-troubleshoot.html", "room": "Troubleshooting without a legal conclusion" }, { "front": "Not advice", "back": "Counsel and the current rule outrank the quiz.", "href": "rooms/T19-compliance-troubleshoot.html", "room": "Troubleshooting without a legal conclusion" }, { "front": "Citation", "back": "The glossary row's authority.", "href": "rooms/T20-glossary-map.html", "room": "Glossary and the mind map" }, { "front": "Mind map", "back": "Topics. Not a network.", "href": "rooms/T20-glossary-map.html", "room": "Glossary and the mind map" }, { "front": "Confirm", "back": "No link when the URL was not opened.", "href": "rooms/T20-glossary-map.html", "room": "Glossary and the mind map" }, { "front": "Next track", "back": "Use the map to pick WebRTC, the open core, or compliance.", "href": "rooms/T20-glossary-map.html", "room": "Glossary and the mind map" }, { "front": "SIPREC", "back": "Fork a session to a recorder. RFC 7866.", "href": "rooms/T20-sister-systems.html", "room": "Sister technologies around the session" }, { "front": "WFM", "back": "Schedules. SIP only shows the symptom, such as 480.", "href": "rooms/T20-sister-systems.html", "room": "Sister technologies around the session" }, { "front": "CRM", "back": "Events and numbers. Not a proxy.", "href": "rooms/T20-sister-systems.html", "room": "Sister technologies around the session" }, { "front": "Twilio docs", "back": "API reference and tutorials. Confirm product names there.", "href": "rooms/T20-sister-systems.html", "room": "Sister technologies around the session" }, { "front": "pjsip.conf", "back": "Asterisk SIP resources.", "href": "rooms/T20-config-troubleshoot.html", "room": "Configuration and troubleshooting seams" }, { "front": "extensions.conf", "back": "Asterisk dialplan.", "href": "rooms/T20-config-troubleshoot.html", "room": "Configuration and troubleshooting seams" }, { "front": "101 first", "back": "No WebSocket, no SIP.", "href": "rooms/T20-config-troubleshoot.html", "room": "Configuration and troubleshooting seams" }, { "front": "Plane", "back": "Name signaling, media, identity, location, or messaging.", "href": "rooms/T20-config-troubleshoot.html", "room": "Configuration and troubleshooting seams" }, { "front": "CUCM trunk", "back": "SIP toward the SBC. Profile is CUCM's object.", "href": "rooms/T20-bridges-map.html", "room": "Bridges from enterprise UC to open platforms" }, { "front": "Local Gateway", "back": "Webex Calling premises PSTN role.", "href": "rooms/T20-bridges-map.html", "room": "Bridges from enterprise UC to open platforms" }, { "front": "Open side", "back": "Kamailio, Asterisk, or FreeSWITCH, per their pages.", "href": "rooms/T20-bridges-map.html", "room": "Bridges from enterprise UC to open platforms" }, { "front": "Not inside CUCM", "back": "The open dialplan stays on the open server.", "href": "rooms/T20-bridges-map.html", "room": "Bridges from enterprise UC to open platforms" }, { "front": "ARI", "back": "Asterisk REST Interface, named with AMI and AGI.", "href": "rooms/T20-future-hooks.html", "room": "Integration hooks that are already named" }, { "front": "Event Socket", "back": "FreeSWITCH programming path in the manual.", "href": "rooms/T20-future-hooks.html", "room": "Integration hooks that are already named" }, { "front": "SIPREC", "back": "Recording hook. RFC 7866.", "href": "rooms/T20-future-hooks.html", "room": "Integration hooks that are already named" }, { "front": "No live connector", "back": "This repository does not run the PBX or the registry.", "href": "rooms/T20-future-hooks.html", "room": "Integration hooks that are already named" } ] }