asterisk users - Jun 2017 - RTP / NAT question with IPv6/IPv4 problem

Hello,

All my asterisk systems use only IPv4 currently.  I have one phone which is on
T-Mobile network,  and this network is only IPv6 now.

The phone can register fine, because T-Mobile does NAT64 and it connects fine to
my IPv4 asterisk server.

But in the SDP for a call setup,  this phone sends only an IPv6 address as a
contact, so RTP fails.


I have nat=yes already set on this chan_sip extension, I thought this would
ignore the IPv6 in the SDP and use the *apparent* IPv4 instead, but apparently
not?

Any help appreciated, thanks all.