The standard method to deploy these files is using the archive command from the privileged EXEC prompt: archive tar /xtract tftp:// /Cme-complete-fileset-12.0.tar flash:
A set of HTML and XML files required to manage the system through a web browser instead of strictly using the CLI.
After extraction, you must configure the router to serve these files to IP phones using the tftp-server flash: command for each firmware file. INSTALL CME 12 IN ROUTER ISR4321/K9 - Cisco Community
Use the show license all command to ensure you have the appropriate Unified Communications (UC) license activated.