Asterisk, Cisco CP-9971, sdp-anat

Hi, all.
Is anybody managed call from Cisco CP-9971 to Asterisk (12.8.0)?
We have that ip phone and call ends with error in log ‘Received SIP INVITE with unsupported required extension: required: unsupported:sdp-anat’.
How to enable sdp-anat in Asterisk?
And there should be some option in xml configuration file for CP-9971 to disable sdp-anat. May be somebody know, what exactly is option?

Asterisk does not support the “sdp-anat” extension so there is no place to enable it. You would indeed have to figure out how to disable it in the XML file for the Cisco. I don’t have experience with that phone so unfortunately I can’t help in that regard but it is the direction you need to go in.

Thanks for the answer