CUCM Phone Firmware Update

  1. Go to, search for your phone model and download the relevant firmware
  2. Copy firmware to a SFTP server (I run Solarwind's free SFTP server on my laptop)
  3. Log into CUCM Pub: OS Administration->Software Upgrade->Install/Upgrade->Remote Filesystem
  4. Go through the steps to connect to SFTP and upload the phone firmware
  5. Repeat steps 3 & 4 on your CUCM Subs
  6. On the Pub and Subs, log into Serviceability->Tools->Control Center - Feature Services
  7. Select the server you are logged into (Pub or Sub)
  8. Restart Cisco Tftp

On 10.5.2, the device defaults update automatically, and next time the phone reboots it will upgrade it's firmware.