Cisco's SIP trunk failure tech note lists out-of-service reason codes: Local=1 means no responses to OPTIONS after all retries over UDP, Local=2 means Unified CM could not open a socket to the remote peer, and Local=3 means DNS could not resolve the hostname or SRV record.

Checked 2026-09-24

Vendor
Cisco
Product
Unified Communications Manager
Subsystem
SIP trunk
Deployment
on-premises
Region
not restricted
Release range
as documented 2018
Checked
2026-09-24

Sources

Cite this note

APA

WarmTransfer. (2026, September 24). SIP OPTIONS pings and trunk keepalives: source note sip-options-keepalive-cucm-no-service-reasons. WarmTransfer. https://warmtransfer.net/knowledge/claims/sip-options-keepalive-cucm-no-service-reasons

BibTeX

@misc{warmtransfer-claim-sip-options-keepalive-cucm-no-service-reasons,
  title  = {SIP OPTIONS pings and trunk keepalives: source note sip-options-keepalive-cucm-no-service-reasons},
  author = {{WarmTransfer}},
  year   = {2026},
  url    = {https://warmtransfer.net/knowledge/claims/sip-options-keepalive-cucm-no-service-reasons},
  note   = {Source note sip-options-keepalive-cucm-no-service-reasons, checked 2026-09-24}
}

Read in context