Given that the 7975G is obsolete, consider:
: The phone fetches the .zip contents (extracted) via TFTP during its boot cycle.
: If your phone is on a very old version (e.g., version 8.x), you may need to upgrade to an intermediate version (like 9.3.1) before moving to 9.4(2)SR4.
Cisco never released an official file named exactly cmterm7975sip942sr4zip . The closest official versions are: