Maybe not too much help, but someone told me this last week. I asked them to undo the OOB CLI and use CCA 2.2 to add the sidecar in the voice configuration, and it worked. Like I said, probably not what you wanted (CLI), but CCA made it work....
I take it you didnt use CCA? CCA does one other thing which is the Crete CNF (under telephony-service).
UC520-lab-1#conf t Enter configuration commands, one per line. End with CNTL/Z. UC520-lab-1(config)#telep UC520-lab-1(config)#telephony-service UC520-lab-1(config-telephony)#cre UC520-lab-1(config-telephony)#create ? cnf-files create XML cnf for ethernet phone
This phone has been in operation for over a year so I wasnt sure how to 'use cca to create it'. I did try removing the 7916 from the 7965 in CCA, appy, then add them back and there was no change.
In the end, once I had a hint as to what the config should be, and the filename, I discovered a file corruption. I deleted the old and uploaded a new copy and it worked.
PS: After using CCA 2.2 yesterday to change the users (the only changes made) it re-wrote and re-organized all the voice-translations resulting in inbound calls being handled strangely (you call in and you get an intercom dialtone, you dial 9 and you can call anywhere you want). So I was up at 1am recovering the system to a previous backup, losing 3 hours of work I had done on the config yesterday. Grrr
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