This is the most common issue when moving from SCCP to SIP on the 7975G.
Are you planning to use this phone with or a third-party system like FreePBX ? SIP configuration on cisco 7975 - FreePBX Community Forums
As noted, if moving from must use an intermediate step.
There are two primary methods to apply this firmware, depending on whether you are using a Cisco Unified Communications Manager (CUCM) or a third-party TFTP server. Method 1: Using Cisco Unified Communications Manager (CUCM) cmterm7975sip942sr4zip upd
Before you begin the upgrade process, it's crucial to check the prerequisites to avoid complications.
The file identifier refers to a specific SIP firmware release for the Cisco Unified IP Phone model 7975G. This package is officially designated as SIP 9.4(2)SR4 .
The you want to connect to (e.g., FreePBX , Asterisk , 3CX ). The current firmware version installed on your phone. This is the most common issue when moving
Disconnect the Ethernet cable (or PoE power) from the back of the 7975G. Hold down the while plugging the power cable back in.
: The archive format intended for manual extraction onto local Trivial File Transfer Protocol (TFTP) engines. This format is preferred when a full Cisco Unified Communications Manager (CUCM) system is unavailable to run a native .cop installer.
Security hardening, image authentication (signed files to prevent tampering), and bug fixes for improved stability on legacy systems. How to Install the Update There are two primary methods to apply this
In the quiet, humming world of server racks and blinking LEDs, cmterm-7975-sip.9-4-2SR4.zip
If your phone is currently running a version older than 8.3(3), you must first upgrade to an intermediate version (like 8.5(2)) before applying version 9.4(2).
Enhanced Signatures, upgraded TLS handling, and SSH management Step-by-Step Update Installation Guide