Call fails with "not acceptable" during call

[technology7]

I have two situations where calls are getting terminated mid-call with a not acceptable message to the user. In one case it happens calling Lenovo and selecting certain options from their phone tree. You hear the person answer and then it fails.
The other just has random failures when leaving voicemail for someone; they will be mid-way through the message and it fails with the same error. One is 3CX 10/sp4 the other sp6. One is broadvox the other CBeyond. I have packet captures and detailed logs from both.
Any ideas would be greatly appreciated.

 

[leejor]

Is a SIP message being set to the called party just before the not acceptable message is sent back to the 3CX end, or is the message being sent back in response to some audio function being performed? Do you have any way of trying this from another set-up, through another provider?

What is the Lenovo number being called (if you don't mind giving it out), and options selected, perhaps some of us can try it and see what happens if it is one of their regular queues and not a private number.