Troubleshoot IP Phone Unregistration Issues in CUCM

Publisher

Cisco

URL

https://www.cisco.com/c/en/us/support/docs/unified-communications/unified-communications-manager-version-115/220670-troubleshoot-ip-phone-unregistration-iss.html

Published

2023-07-28

Updated

unknown

Accessed

2026-09-24

HTTP status

200

License

Cisco website terms of use; no-redistribution; short excerpts and locators only

Source notes citing this source

• When the Unified CM cluster is in non-secure mode, the TFTP server answers the phone's CTL file request with 404 Not Found. in context
• Phone registration depends on DHCP, DNS, TFTP, the voice VLAN and PoE in addition to Unified CM itself. in context
• Unified CM event viewer logs record EndPointUnregistered alarms carrying device name, IP address, protocol, device type and a reason code, and TAC advises focusing on the reason number, MAC address and timestamp. in context
• After the CTL request the phone requests the ITL file, which the TFTP server returns with 200 OK, and then requests its configuration file. in context
• For unregistration issues Cisco TAC lists the phone's Problem Report Tool (PRT) or console logs from the phone, and CallManager traces, event viewer logs and TFTP logs from Unified CM, as the data to collect. in context
• Cisco TAC advises establishing the affected phone models, locations, number of phones and firmware versions, and noting several affected MAC addresses and the time the issue started, before troubleshooting unregistration. in context
• A successful SIP phone registration appears as the phone's REGISTER answered by SIP/2.0 200 OK carrying the contact and an expiry; the tech note's example shows 120 seconds. in context

Cite this source record

APA

WarmTransfer. (2023, July 28). Troubleshoot IP Phone Unregistration Issues in CUCM. WarmTransfer. https://warmtransfer.net/knowledge/sources/cisco-technote-220670-phone-unregistration

BibTeX

@misc{warmtransfer-cisco-technote-220670-phone-unregistration,
  title  = {Troubleshoot IP Phone Unregistration Issues in CUCM},
  author = {{WarmTransfer}},
  year   = {2023},
  url    = {https://warmtransfer.net/knowledge/sources/cisco-technote-220670-phone-unregistration},
  note   = {Cisco, accessed 2026-09-24}
}