I have external IP that have domain name (for example sip.myserver.com). 

I see error at log - bad_uri sip.myserver.com

I think it happens because kamailio does not know atything about external ip pecause kamamiliol working with server interfaces (eth0, eth1, etc.)

So my question - how to listen external IP with domain name on kamailio that running behind NAT?

P.S. I do not have any access to router, that present NAT for me.