Cmterm-7975-sip.9-4-2sr4

If your organization runs CUCM 9.1(2) or 10.5(2), you cannot upgrade to the latest 7975 firmware (e.g., 9.4(3) or 9.4(4)) without risking incompatible device packs. The 9.4(2)SR4 build is often the last compatible load for these older call managers.

Cisco Unified Serviceability > Tools > Control Center - Feature Services and restart the Cisco Tftp Device > Phone , select your , and update the Phone Load Name cmterm-7975-sip.9-4-2sr4