Cisco Support Community
Community Member

Oneway communication

Attached is debug of call.

config on mgcp router

Outbound calls complete but they can't hear me, I hear them!



Re: Oneway communication

The call setup is OK, so your Call Manager to gateway and PRI is good, as well as to the phone.

It appears your phone is unable to send packets to the MGCP router. Try an extended ping from the gateway router to your phone sourcing packets from FastEthernet0/0.108. If this fails, confirm that your phone has the correct default gateway. If it does try a traceroute from the router on your phone's subnet to the gateway router.

Do you have any security filtering that may be blocking packets?

Community Member

Re: Oneway communication

I do have some access-lists, just those listed as mustdo's in Internetworking docs. Applied them towards the multilink interface though. Strange thing is that it seems access-lists were created on a core switch that don't seem to be applied. I configured this switch via a Cisco automated program.

Can any of the attached configs add up to blocked packets. Strange thing is that I can ping all over the darn place! to and from from all the pertainite interfaces and ofcourse from the CCM.

Let me know if their is any other items needed for complete view of problem. Thanks

Cisco Employee

Re: Oneway communication

Is SBB_AR_FM1 a different GW from the previous post where you provided MGCP.txt?

I ask because the config now has this:

mgcp bind control source-interface FastEthernet0/0

mgcp bind media source-interface FastEthernet0/0

FA0/0 does not have an IP Address assigned.

In your other conversation you noted that inbound calls work but outbound calls have one way audio. Is this still the case?

Try and inbound test call then an outbound test call. After the inbound call web into the IP Address of the phone, for example http://. On the left side click on the "Stream 1" link. Note the remote address and port. Do the same after the outbound call. What is different between the two (the port will be different just want to see what it is)?


Community Member

Re: Oneway communication

Good catch, I had sent you an old file. Sorry.

The interface is fa0/0.108(attached updated file)

I tested as you suggested. Same issue. (ofcourse)

The local and remote addresses stayed the same in both senarios, however the remote tcp/udp ports changed. I have tried this multiple times and seems to change arbitrarily. Did that provide any more insight?


Re: Oneway communication

The audio path is directly between the IP phone and the gateway. The control path is between the Call Manager and the endpoints, so be sure that you can ping between the gateway router and the phone. It may be that the phone can communicate with the Call Manager, but only one way to the gateway.

I would suggest removing security access lists until you get the calls working.

Cisco Employee

Re: Oneway communication

You might be having a DSP issue. Not sure what platform you have. See if this page helps you to verify whether the DSPs are good or not.


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