Source note · SIP 503 and trunk out-of-service failures
A Unified CM trunk Status Reason of local=3 means DNS resolution failed (DNS server unreachable or DNS misconfigured).
Checked 2026-09-25
- Vendor
- Cisco
- Product
- Unified Communications Manager
- Subsystem
- trunk status and alarms
- Deployment
- on-premises
- Region
- not restricted
- Release range
- as documented in 2018 tech note
- Checked
- 2026-09-25
Sources
- Calls through Session Initiation Protocol (SIP) Trunk Failure — Cisco · tier 2 current vendor documentation · Scenario local=3
Cite this note
APA
WarmTransfer. (2026, September 25). SIP 503 and trunk out-of-service failures: source note sip-503-trunk-failures-cucm-local-3-dns. WarmTransfer. https://warmtransfer.net/knowledge/claims/sip-503-trunk-failures-cucm-local-3-dns
BibTeX
@misc{warmtransfer-claim-sip-503-trunk-failures-cucm-local-3-dns,
title = {SIP 503 and trunk out-of-service failures: source note sip-503-trunk-failures-cucm-local-3-dns},
author = {{WarmTransfer}},
year = {2026},
url = {https://warmtransfer.net/knowledge/claims/sip-503-trunk-failures-cucm-local-3-dns},
note = {Source note sip-503-trunk-failures-cucm-local-3-dns, checked 2026-09-25}
}