Source note · Enabling mixed mode and encrypted calling in Unified CM
After a change to non-secure mode the CTL file still exists on servers and phones but contains no CCM+TFTP server certificates, and Cisco recommends deleting the CTL file from phones to avoid problems if certificates or cluster topology later change.
Checked 2026-09-30
- Vendor
- Cisco
- Product
- Cisco Unified Communications Manager
- Subsystem
- CTL
- Deployment
- on-premises
- Region
- not restricted
- Release range
- 10.x and later
- Checked
- 2026-09-30
Sources
- CUCM Cluster Changed from Mixed Mode to Non-Secure Mode Configuration Example — Cisco Systems · tier 2 current vendor documentation · Background / CTL file after non-secure mode
Cite this note
APA
WarmTransfer. (2026, September 30). Enabling mixed mode and encrypted calling in Unified CM: source note cucm-secure-calling-setup-nonsecure-ctl-remains. WarmTransfer. https://warmtransfer.net/knowledge/claims/cucm-secure-calling-setup-nonsecure-ctl-remains
BibTeX
@misc{warmtransfer-claim-cucm-secure-calling-setup-nonsecure-ctl-remains,
title = {Enabling mixed mode and encrypted calling in Unified CM: source note cucm-secure-calling-setup-nonsecure-ctl-remains},
author = {{WarmTransfer}},
year = {2026},
url = {https://warmtransfer.net/knowledge/claims/cucm-secure-calling-setup-nonsecure-ctl-remains},
note = {Source note cucm-secure-calling-setup-nonsecure-ctl-remains, checked 2026-09-30}
}