Source note · Calls that drop after about 30 seconds
Cisco gives a common cause of SIP calls dropping at 15 minutes: the TCP timeout on firewalls or routers is shorter than the SIP session expires timer. It also says network devices that intercept refresh messages can cause the failure.
Checked 2026-09-25
TCP timeout configured on the network (firewalls, routers) is less than the SIP session expires timer.
- Vendor
- Cisco
- Product
- Unified Communications Manager
- Subsystem
- session timer / network
- Deployment
- on-premises
- Region
- not restricted
- Release range
- as documented 2015-07-23
- Checked
- 2026-09-25
Sources
- Troubleshoot Call Failures on TC Endpoints Registered to Cisco CallManager — Cisco · tier 2 current vendor documentation · Section 'Problem: SIP Call Drop after 15 Minutes', cause paragraph
Cite this note
APA
WarmTransfer. (2026, September 25). Calls that drop after about 30 seconds: source note sip-calls-drop-30-seconds-cucm-15min-firewall-tcp. WarmTransfer. https://warmtransfer.net/knowledge/claims/sip-calls-drop-30-seconds-cucm-15min-firewall-tcp
BibTeX
@misc{warmtransfer-claim-sip-calls-drop-30-seconds-cucm-15min-firewall-tcp,
title = {Calls that drop after about 30 seconds: source note sip-calls-drop-30-seconds-cucm-15min-firewall-tcp},
author = {{WarmTransfer}},
year = {2026},
url = {https://warmtransfer.net/knowledge/claims/sip-calls-drop-30-seconds-cucm-15min-firewall-tcp},
note = {Source note sip-calls-drop-30-seconds-cucm-15min-firewall-tcp, checked 2026-09-25}
}