The file is a specific firmware update package for the Cisco Unified IP Phone 7975G Go to product viewer dialog for this item.
| Symptom | Likely Cause | Solution | | :--- | :--- | :--- | | Phone stuck at “Upgrading” loop | Corrupted download or TFTP timeout | Restart TFTP service on CUCM; re-upload the ZIP file. | | Phone reverts to old firmware | DHCP Option 150 or 66 points to wrong TFTP server | Verify DHCP scope settings; ensure the correct CUCM TFTP IP is provided. | | “Authentication Error” on phone | Load file signature mismatch (older CUCM doesn’t trust new firmware) | Install the latest on CUCM, not just the firmware. | | Phone fails to register after update | SIP parameters changed (e.g., SIP port, transport) | Factory reset the phone ( Settings > Admin Settings > Reset Settings ) and reprovision. | cmterm7975sip942sr4zip upd