Three ways a call can enter · Learn it in 5 minutes

SIP and carriers · foundation · 12 min full read

The technical requirements describe three SIP stories. Five9 can provide ITSP trunks. Your ITSP can connect to Five9 session border controllers, and there is a checklist for that. Or a gateway you already own — Avaya, Cisco, or Asterisk — can talk to Five9 over the internet, a VPN, or Direct Connect.

Name the three SIP stories

Refuse to treat a Cisco gateway as a UCCX import

Cisco in that sentence is a gateway type, not a promise that a UCCX script will import. Pick the story before you draw a codec or a DNIS.

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 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.
ITU-T E.164, international public telecommunication numbering. standard. last checked 2026-10.