Ok, so I spent probably a week and half banging my head against the keyboard trying to figure out why my Polycom 601 wasn't receiving audio from an FXO voice-port connected to the PSTN on my Cisco 2620XM router/gateway. I can't tell you how many times I typed show run, scratched my head, ran trace after trace, only to find myself at Cisco's IP Communications and Video Forum. Here I started search "one way audio". Well, this is where I found my silver bullet.
I finally came across a response to a post about a one way audio problem. The responder referenced Troubleshooting One Way Voice Issues. OMFG! All I had to do was read the title to the Ensure That IP Routing Is Enabled on the Cisco IOS Gateway and Routers section to realize that in the show run was no ip routing. Well, one quick change to that and blamo! Voice! Now all I have to resolve is some echo issues, but that shouldn't be too difficult.
