T2 · T2-R04
SIP trunks on CUCM
Learn it in 5 minutes
- The trunk, the SIP profile, and the security profile are three objects.
- OPTIONS can mark a trunk out of service.
- Early offer is a setting, not a guess.
- Run on all nodes is a choice with consequences.
- A trunk in service can still route nowhere if the CSS is empty.
Visual
What is going on
CUCM sends OPTIONS when the profile says so. A trunk that looks down may be a failed OPTIONS to an address that does not answer, while calls would have worked, or the reverse. Read the destination address and the profile together.
Confirm before relying. Confirm OPTIONS defaults in your CUCM version.
Worked example
A new CUBE peer answers calls but CUCM marks the trunk down. The OPTIONS ping target is a different IP than the INVITE target. Fix the target you actually configured, then retest.
Quiz
1. A SIP trunk in service proves the route pattern points at it.
False. Routing and status are separate.
Ecosystem
Sister pieces sit on the ecosystem page: the glossary, the mind map, the integration map, and the sibling labs.
- SIP trunk — CUCM's signaling peer toward a gateway or another call agent.
- SIP profile — Timers, OPTIONS, and offer behavior for that trunk.
Config. Record profile name, security profile, destination, and CSS.
Troubleshooting. Compare a failed call's SIP cause with the trunk status at that minute.
Bridge. The local gateway trunk toward Webex Calling is still a SIP trunk with its own profile. Confirm the Webex guide.
Mind map, sister technologies, and future hooks live on the ecosystem page.
Sources
Product screens move. Confirm the guide for your release before you change a live system.
Sources and go deeper
Opened 2026-10. A row marked confirm has no link, because that page was not verified.
- RFC. RFC 3261, SIP last checked 2026-10
- RFC. RFC 4028, SIP session timers last checked 2026-10
- Cisco. Cisco Unified Communications Manager product support last checked 2026-10
- Cisco. System Configuration Guide for CUCM, Release 15 last checked 2026-10
- Protocol and ports. CUCM 15 TCP and UDP port usage last checked 2026-10
- Protocol and ports. IANA SIP parameters last checked 2026-10
- Community. Cisco Community, Collaboration knowledge base last checked 2026-10
- Wikipedia. Session Initiation Protocol (Wikipedia) last checked 2026-10
- Cisco. Collaboration 12 SRND book. confirm. The historical Collaboration 12 SRND path opened as a product listing, not the design book. Use the Preferred Architecture index, which was opened. last checked 2026-10