Source note · Planning a Unified CM upgrade
Before upgrading Unified CM to Release 15, Cisco Wireless IP Phone 8821 and 8821-EX handsets need firmware 11.0(5)SR3 or later.
Checked 2026-09-25
ensure that the firmware is updated to a minimum version of 11.0(5)SR3 before upgrading Unified Communications Manager to Release 15.
- Vendor
- Cisco
- Product
- Unified Communications Manager
- Subsystem
- phone firmware
- Deployment
- on-premises
- Region
- not restricted
- Release range
- destination Release 15
- Checked
- 2026-09-25
Sources
- Upgrade and Migration Guide for Cisco Unified Communications Manager and the IM and Presence Service, Release 15 and SUs - Planning the Upgrade — Cisco Systems · tier 2 current vendor documentation · Planning the Upgrade > Requirements and Limitations (8821 note)
Cite this note
APA
WarmTransfer. (2026, September 25). Planning a Unified CM upgrade: source note cucm-upgrade-planning-8821-firmware-minimum. WarmTransfer. https://warmtransfer.net/knowledge/claims/cucm-upgrade-planning-8821-firmware-minimum
BibTeX
@misc{warmtransfer-claim-cucm-upgrade-planning-8821-firmware-minimum,
title = {Planning a Unified CM upgrade: source note cucm-upgrade-planning-8821-firmware-minimum},
author = {{WarmTransfer}},
year = {2026},
url = {https://warmtransfer.net/knowledge/claims/cucm-upgrade-planning-8821-firmware-minimum},
note = {Source note cucm-upgrade-planning-8821-firmware-minimum, checked 2026-09-25}
}