I am trying to call from remote soft phone to another extension on local network.
While i can make call from local extension to remote softphone, other way round is not possible.
Also i am not able to dial external numbers from remote softphone.
You are trying to set up encrypted media, but sending the encryption keys over an open (UDP) channel. Whilst I’m surprised Asterisk allows you to try, the endpoint is simply stopping your making a big mistake.
Maybe the endpoint is registering with SIP: contact addresses?
I got the direction of the call wrong above, and have corrected it.
Now that you point out the local address, I think we can safely say you have SIP ALG (application level gateway) in the router. This should be disabled, as, as in this case, it is typically badly implemented.
Sorry, I wasn’t thinking straight. You should see the internal destination address. The only problem is that you are getting not acceptable here for SDP, and that is pretty obviously because you are trying to invoke SRTP in an unsafe way. Even if Asterisk allows this, you should not do it.
You will need symmetric RTP enabling. I can’t remember what the default is. That is because the phone is failing to compensate for being behind NAT. You might want to look into whether the phone supports STUN.