Source note · Troubleshooting Cisco IP phones stuck upgrading firmware
A third-party load server must be able to serve every file the phone requests over HTTP on TCP port 6970 (preferred) or over UDP-based TFTP.
Checked 2026-10-02
A third-party server must be capable of providing any files the phone requests through HTTP on TCP Port 6970 (preferred) or the UDP-based TFTP protocol.
- Vendor
- Cisco
- Product
- Cisco Unified Communications Manager
- Subsystem
- load server
- Deployment
- on-premises
- Region
- not restricted
- Release range
- 15 and SUs
- Checked
- 2026-10-02
Sources
- Administration Guide for Cisco Unified Communications Manager, Release 15 and SUs - Manage Device Firmware — Cisco Systems · tier 2 current vendor documentation · Using a Load Server
Cite this note
APA
WarmTransfer. (2026, October 2). Troubleshooting Cisco IP phones stuck upgrading firmware: source note cucm-phone-firmware-upgrade-troubleshooting-loadsrv-3rdparty. WarmTransfer. https://warmtransfer.net/knowledge/claims/cucm-phone-firmware-upgrade-troubleshooting-loadsrv-3rdparty
BibTeX
@misc{warmtransfer-claim-cucm-phone-firmware-upgrade-troubleshooting-loadsrv-3rdparty,
title = {Troubleshooting Cisco IP phones stuck upgrading firmware: source note cucm-phone-firmware-upgrade-troubleshooting-loadsrv-3rdparty},
author = {{WarmTransfer}},
year = {2026},
url = {https://warmtransfer.net/knowledge/claims/cucm-phone-firmware-upgrade-troubleshooting-loadsrv-3rdparty},
note = {Source note cucm-phone-firmware-upgrade-troubleshooting-loadsrv-3rdparty, checked 2026-10-02}
}