Cisco says to delete a phone's ITL only when all four hold: the phone's ITL signature differs from the CUCM ITL, the TVS signature in the ITL differs from the certificate TVS presents, downloads show Verification Failed, and no backup of the old TFTP private key exists.
Checked 2026-10-01
- Vendor
- Cisco
- Product
- Unified Communications Manager
- Subsystem
- ITL
- Deployment
- on-premises
- Region
- not restricted
- Release range
- 8.0 and later
- Checked
- 2026-10-01
Sources
- Understand CUCM Security By Default and ITL Operation and Troubleshooting — Cisco Systems · tier 2 current vendor documentation · Troubleshoot section (when to delete the ITL)
Cite this note
APA
WarmTransfer. (2026, October 1). Troubleshooting phone trust and ITL failures in Unified CM: source note cucm-itl-trust-troubleshooting-itl-delete-conditions. WarmTransfer. https://warmtransfer.net/knowledge/claims/cucm-itl-trust-troubleshooting-itl-delete-conditions
BibTeX
@misc{warmtransfer-claim-cucm-itl-trust-troubleshooting-itl-delete-conditions,
title = {Troubleshooting phone trust and ITL failures in Unified CM: source note cucm-itl-trust-troubleshooting-itl-delete-conditions},
author = {{WarmTransfer}},
year = {2026},
url = {https://warmtransfer.net/knowledge/claims/cucm-itl-trust-troubleshooting-itl-delete-conditions},
note = {Source note cucm-itl-trust-troubleshooting-itl-delete-conditions, checked 2026-10-01}
}