dhfobi,
OBi is sending
out packets on port 19305. Port forwarding that port to the OBi might be irrelevant, as suggested by the OP, no port forwarding is involved in his solution. However if you read further, Google support site mentions something about Google servers sending packets back to the client to same port. Perhaps making port forwarding relevant after all.
Quote:
"All traffic back to the client from our conference servers will originate from the same port that the client is sending to, and be directed back to the port that the client is sending from."
Looking for info on port 19305 we find references to Google hangout. At first it might seem unrelated to Google voice or GTalk, however it makes references to many of the ports the OP had mentioned.
See:
http://support.google.com/a/bin/answer.py?hl=en&answer=1279090Summary:
The connection methods are attempted in this preferenced order:
1) A UDP connection from the participant to Google on ports 19305 through 19309
2) A TCP connection from the participant to Google on ports 19305 through 19309
3) A TCP connection from the participant to Google on port 80
4) A TCP connection from the participant to Google on port 443 (SSL)
The ideal connection for a user to make to a hangout is through UDP. To allow this connection attempt to succeed you will need to allow connections into your network from UDP ports 19305 through 19309.
All traffic back to the client from our conference servers will originate from the same port that the client is sending to, and be directed back to the port that the client is sending from.
At a minimum, your corporate network must allow access to the Internet on TCP ports 80 and 443 in order for hangouts to work.
Another site analyzed the TCP connections of Google hangout. An interesting observation in his analysis is there are references that Google hangouts uses GTalk with a destination port 19305.
http://www.coolacid.net/20110701219/Latest/google-hangout-detailsSince OBi support mentioned an upcoming firmware fix, port forwarding might not be the cause. I think OBihai just discovered a detail in the GTalk protocol.