Source note · Troubleshooting Cisco IP phone registration
Cisco recommends DHCP custom option 150 for IPv4 devices to learn the TFTP server address, lists DHCP option 066 and CiscoCM1 as alternatives it does not recommend, and uses Cisco vendor-specific DHCPv6 information for IPv6.
Checked 2026-09-24
- Vendor
- Cisco
- Product
- Unified Communications Manager
- Subsystem
- TFTP discovery
- Deployment
- on-premises
- Region
- not restricted
- Release range
- 12.5(1)SU1
- Checked
- 2026-09-24
Sources
- System Configuration Guide for Cisco Unified Communications Manager, Release 12.5(1)SU1 - Configure TFTP Servers — Cisco · tier 2 current vendor documentation · Configure TFTP Servers > TFTP server overview / finding the TFTP server
Cite this note
APA
WarmTransfer. (2026, September 24). Troubleshooting Cisco IP phone registration: source note cisco-phone-registration-troubleshooting-opt150-rec. WarmTransfer. https://warmtransfer.net/knowledge/claims/cisco-phone-registration-troubleshooting-opt150-rec
BibTeX
@misc{warmtransfer-claim-cisco-phone-registration-troubleshooting-opt150-rec,
title = {Troubleshooting Cisco IP phone registration: source note cisco-phone-registration-troubleshooting-opt150-rec},
author = {{WarmTransfer}},
year = {2026},
url = {https://warmtransfer.net/knowledge/claims/cisco-phone-registration-troubleshooting-opt150-rec},
note = {Source note cisco-phone-registration-troubleshooting-opt150-rec, checked 2026-09-24}
}