Foundations and how to read a call

Rooms

1. What SIP is for

   SIP creates, changes, and ends sessions, while RTP carries the media those sessions describe.

2. Ports, transports, and where a request can go

   SIP uses UDP or TCP on 5060 and TLS on 5061, and a request that does not fit one datagram needs a connection.

3. E.164, sip URIs, and tel URIs

   A global number is written in a tel URI or in a sip URI user part, and E.164 is the numbering plan those digits follow.

4. How to read an RFC

   A SIP argument cites the RFC number and the section, and the normative sentences outrank a broken example.

5. The hitchhiker guide is a map

   RFC 5411 is an informational map of the SIP document set, and it does not replace the base specification.

6. Licenses, codecs, and what you may copy

   Protocol text is under the IETF trust provisions, and codec rights have to be read from the codec's own documents.

7. Reading the first INVITE

   The first INVITE has a magic-cookie branch, Max-Forwards 70, a From tag, and no To tag.

Ecosystem

SIP does not replace workforce management, quality monitoring, CRM, emergency policy, or a messaging registry. It is the session seam those systems hang from. Compliance notes on this page are educational and are not legal advice.

Open the map