DNS, codecs, and the default voice · Learn it in 5 minutes

The requirements prefer DNS SRV for the SIP targets. G.711 is the default codec, and the PDF describes it as uncompressed. Do not invent a packetization time. A 20 millisecond ptime shows up in practitioner notes about Cisco gateways. It is not a number this lab will attribute to the Five9 PDF.

RFC 3261 is the SIP signaling baseline. RFC 4733 is the telephone-event way digits often ride once the call is up. DTMF design is a separate sentence from the codec.

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.