I just got a couple of Polycom 301 phones to use with our system, to replace the poor quality Grandstream BudgeTone 101s we had originally bought. The Polycom 301 I’m using for testing has a problem: whenever I call either an internal extension or an external number from the Polycom phone the other end can hear me but the Polycom receives no audio from the other end. If either an internal or external call comes into the Polycom, everything is fine. Our Asterisk systems run fine with all the Sipura 2000/2002 boxes we have(and the BudgeTones were fully functional, just really bad quality).
[SOLVED] While I was writing this, I wanted to go over all the settings one more time before I posted. What I hadn’t seen up until now was the NAT settings. Setting the IP to our external IP, the signalling port to something, and the media port to something fixed the problem. For testing purposes, I set the signaling port to 64646, and the media port to 46464. I figure any random port between 1024 and 65535 will work.