Cisco Unified Communications Manager Trunks (Session Management Edition deployment guide, Release 8.5(1))

Publisher

Cisco Systems

URL

https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/cucm/session_mgmt/deploy/8_5_1/trunks.html

Published

unknown

Updated

unknown

Accessed

2026-10-02

HTTP status

200

License

Cisco copyright; all rights reserved; no-redistribution; short excerpts and locators only

Source notes citing this source

• When all destinations of a SIP trunk are unreachable, Unified CM considers the SIP trunk out of service. in context
• With OPTIONS ping enabled, Unified CM sends trunk calls only to destinations it has found reachable. in context
• The SIP trunk is considered in service when at least one node receives a response other than 408 or 503 from at least one destination address. in context
• Under the documented in-service rule, a far end that answers OPTIONS with an error other than 408 or 503 (for example 404 or 405) would still keep the destination in service. inferred in context
• With SIP OPTIONS ping, a trunk destination address is considered out of service if it does not respond to an OPTIONS request, answers 503 Service Unavailable or 408 Request Timeout, or a TCP connection cannot be established. in context
• With OPTIONS ping enabled, each Unified CM node running the trunk's SIP daemon periodically sends an OPTIONS request to each of the trunk's destination IP addresses. in context
• Cisco recommends enabling SIP OPTIONS ping on all SIP trunks so Unified CM tracks trunk state dynamically rather than per call and by timeout. in context
• A trunk can show No Service while utils network ping to the peer succeeds, because OPTIONS ping also fails on 503 or 408 answers, on TCP connect failure and on a wrong destination port, none of which ICMP tests. inferred in context

Cite this source record

APA

WarmTransfer. (2026, October 2). Cisco Unified Communications Manager Trunks (Session Management Edition deployment guide, Release 8.5(1)). WarmTransfer. https://warmtransfer.net/knowledge/sources/cisco-cucm-sme-851-trunks

BibTeX

@misc{warmtransfer-cisco-cucm-sme-851-trunks,
  title  = {Cisco Unified Communications Manager Trunks (Session Management Edition deployment guide, Release 8.5(1))},
  author = {{WarmTransfer}},
  year   = {2026},
  url    = {https://warmtransfer.net/knowledge/sources/cisco-cucm-sme-851-trunks},
  note   = {Cisco Systems, accessed 2026-10-02}
}