DNS, codecs, and the default voice

DNS, codecs, and the default voice · Worked example

Split the ticket

Write the PDF facts and the practitioner note on two lines.

SRV and G.711

ptime as uncertain

RFC 4733 if DTMF matters

A reader can see which line is official.

DNS? SRV preferred.

Default codec? G.711.

20 ms? Practitioner, uncertain, not a PDF quote here.

Digit RFC? 4733.

Sources and go deeper

Technical requirements PDF. vendor. last checked 2026-10. Fetched for this lab in October 2026. Re-read before you buy hardware or open a firewall.
SIP trunk options chapter. vendor. last checked 2026-10.
RFC 3261. rfc. last checked 2026-10.
RFC 4733. rfc. last checked 2026-10.
RFC 3550, RTP. rfc. last checked 2026-10.
RFC 3551, RTP profile for audio and video. rfc. last checked 2026-10.
ITU-T G.711. standard. last checked 2026-10.
RFC 1035, domain names. rfc. last checked 2026-10.
RFC 2782, DNS SRV. rfc. last checked 2026-10.
confirm. A 20 ms packet time is a practitioner note about Cisco gateways, not a figure quoted from the Five9 technical requirements in this lab. last checked 2026-10.