Nasim,
Unfortunately, this oversight in the pre-sales process puts you in a bad spot. No, the 7916 is not compatible with the 7970. To my knowledge, there is no way to force this either as it would likely take some firmware hacking that would compromise any support you've purchased on the devices as well as the stability of your system.
Here's what you likely can do...work with your Cisco AM to swap either the 7916's or 7970's out for a compatible device. Pesonally, I have always found the 7970 to be one of the more "buggy" phones to deal with...so I'd recommend swapping those out for different model phones...but ultimately this would become a business decision.
Hailey
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