Quote Originally Posted by caseydoug View Post
Putting the device in the router's DMZ will prevent the router from blocking the ports. The biggest problem, however, is not that the router is blocking the ports, but that the router doesn't know what port to send the packet to, so the packet gets lost, not blocked.

I am not an expert on SIP protocol, but I thought it was part of the SIP call setup for the adapter and the server to determine what RTP port would be used, at least initially. Why doesn't this apply even when VOIPo does not proxy its own audio?
I'm not sure of the specifics, but all I know is that most newer routers handle the traffic incorrectly and in our logs we see it blocked at the router when people report those issues. Old routers handle it perfectly fine. New ones try to do all this crazy stuff and analyze/rewrite/direct every single packet and do it incorrectly most of the time.