I have a customer with a natted Yealink T20P...
One rang, one didn't. The local information for the phones is the same -- so NAT seems to be handled properly. Is this an issue with the remote router dropping packets or something...?
I see 4 inbound calls to that device today, and 1 of them doesn't have a progress stamp so I assume that's the same as above -- it never got a 180 back.
I think I can dig up the actual sip traces, if that matters, but it's not in the most convenient of formats.
Some illumination would be appreciated.