First of all, you have to determine whether the 5060 port is accessible, judge the way, and look at the package. If it is TCP and port 5060 is unreachable, the TCP link will not pass.

Secondly, to see if SIP works, you need to grab packets to observe the SIP signaling interaction. If the signaling interaction is normal, that is, there is an INVITE-200 OK-ACK, then it is not a SIP problem.

Finally, let's see if the media is connected.

There is something wrong with any of the above steps, and you can't see the video.