In Unified CM 15, Error 201 Authentication Error on the phone during Extension Mobility login means the user ID or PIN entered was not accepted; the fix is to confirm the correct user ID and PIN with the administrator.
Checked 2026-10-02
- Vendor
- Cisco
- Product
- Cisco Unified Communications Manager
- Subsystem
- Extension Mobility
- Deployment
- on-premises
- Region
- not restricted
- Release range
- 15 and SUs
- Checked
- 2026-10-02
Sources
- Feature Configuration Guide for Cisco Unified Communications Manager, Release 15 and SUs - Extension Mobility — Cisco Systems · tier 2 current vendor documentation · Troubleshooting Extension Mobility > Authentication Error
Cite this note
APA
WarmTransfer. (2026, October 2). Troubleshooting Extension Mobility login failures in Unified CM: source note cucm-extension-mobility-troubleshooting-err-201-auth. WarmTransfer. https://warmtransfer.net/knowledge/claims/cucm-extension-mobility-troubleshooting-err-201-auth
BibTeX
@misc{warmtransfer-claim-cucm-extension-mobility-troubleshooting-err-201-auth,
title = {Troubleshooting Extension Mobility login failures in Unified CM: source note cucm-extension-mobility-troubleshooting-err-201-auth},
author = {{WarmTransfer}},
year = {2026},
url = {https://warmtransfer.net/knowledge/claims/cucm-extension-mobility-troubleshooting-err-201-auth},
note = {Source note cucm-extension-mobility-troubleshooting-err-201-auth, checked 2026-10-02}
}