Connection voice problem between 2 cisco 3640 routers

[ESilva]

I have a voice problem between 2 cisco 3640 routers. The problem is that only in one side of a router can hear the voice of a person, but in the other side cant's hear nothing. I'm using the 12.05 XK1 version in both routers.
I'm using 2 FXS in both routers.
Voice over IP
The serials are configured over Frame Relay [sig][/sig]

 

[BusinessPhoneSystems]

Sounds like a strange one!
Might be worth starting to swap hardware components to see if something might be broke!
Are these routers live or can you get them into the lab? If you can then it may be worth getting a female cable and connecting the serial ports back to back and check that it is not a quality of services issue!
Have you got a smartnet agreement, if so, give them hell!

I am sure that I have not been of much use but I wish you luck, and let us know how you get on!