Asterisk,SIP Retransmission timeout

Question

I have created a sip trunk from One Asterisk(version 11.2.1) say \'A\' server to another Asterisk server(11.7.0) say \'B\', and I am getting sip response 200 ok.
But when I

Answer 1

These incidents usually associated with NAT problems.

If you're sure that this isn't your problem, take a look at router configuration. Some routers are configured by default with "SIP ALG" option.

In some cases, this option should be off because implementation is incomplete.

Try it, and let me known if it works properly.