Cisco's Unified CM 12.5(1) security guide says to use UDP as the SIP trunk outgoing transport only when the far end does not support TCP, and otherwise to use TCP as the default.
Checked 2026-10-02
- Vendor
- Cisco
- Product
- Cisco Unified Communications Manager
- Subsystem
- SIP trunk security profile
- Deployment
- on-premises
- Region
- not restricted
- Release range
- 12.5(1)
- Checked
- 2026-10-02
Sources
- Security Guide for Cisco Unified Communications Manager, Release 12.5(1) - SIP Trunk Security Profile Setup — Cisco Systems · tier 2 current vendor documentation · Table 1 SIP Trunk Security Profile Configuration Settings, Outgoing Transport Type note
Cite this note
APA
WarmTransfer. (2026, October 2). Troubleshooting failed calls caused by large SIP messages over UDP: source note sip-fragmentation-troubleshooting-cucm-outgoing-tcp-default. WarmTransfer. https://warmtransfer.net/knowledge/claims/sip-fragmentation-troubleshooting-cucm-outgoing-tcp-default
BibTeX
@misc{warmtransfer-claim-sip-fragmentation-troubleshooting-cucm-outgoing-tcp-default,
title = {Troubleshooting failed calls caused by large SIP messages over UDP: source note sip-fragmentation-troubleshooting-cucm-outgoing-tcp-default},
author = {{WarmTransfer}},
year = {2026},
url = {https://warmtransfer.net/knowledge/claims/sip-fragmentation-troubleshooting-cucm-outgoing-tcp-default},
note = {Source note sip-fragmentation-troubleshooting-cucm-outgoing-tcp-default, checked 2026-10-02}
}