One Way Audio - IP Phone to PSTN

[droessler]

I am calling a customer and we are getting one way audio - we can hear them, they cannot hear us. Also, when their AA picks up it is not recognizing DTMF input. This is only happening on this one customer number and I suspect it is on their end, however I want to make sure that the problem is not us. I have asked Telco to review call details and check out T1 and they reported no problems found (yet..). Any suggestions to help me verify it is not us?

We are running ICS7750 w/ CM 3.0(8). Gateways are using IOS build 12.2(1)XD1, phones are 7960, and calls are going out over a dedicated voice T1 CAS

[patrickv]

Make sure that on your gateway (cisco IOS box) that routing is enabled. If not this will result in single way voice. Make sure the "ip routing" command is visible in the running config. This may sound very stupid, but you can easilly look over it, especially if the box only has a single ethernet interface and therefore should not do routing. But nevertheless "ip routing" should be enabled.

[droessler]

Even if the call is going "out of network" from gateway to PSTN? Currently I do not have any IP routing enabled on the gateway.

ipphone--CCM--MRP200---TELCO/PSTN---PBX---analogphone

[cstewart]

I had a similar problem. I had to add this statement to an ethernet interface on my router. This inteface is the gateway for my pstn calls.

h323-gateway voip bind srcaddr 10.1.1.1 (this ip is addres of inteface). Hope it helps.

[abertram]

Cstewart is correct. The H.323 gateway needs to be bound to an interface, be it physical or the loopback interface. Note the command he brought up above 'h323-gateway voip bind srcaddr x.x.x.x .

We are currently troubleshooting problems with no audio cut through in both directions on our dual PRI card and have tried this statement with no luck, so I understand the frustrations.

Cheers.