Cisco IP Phone 7921G

[excel_aguila]

Hi,

We currently have one Cisco 7921G wireless IP Phone and we would like to use it outside our corporate network. We set up our ASA5510 with phone proxy to our CUCM and the phone can register to the CUCM and gets the extension. However, there are no incoming and outgoing audio when we try to use it. However, if we try to connect it inside the corporate wireless network, it's working fine. Anybody has any idea?

Model     :     CP-7921G

App Load ID     :     1.3.3.LOADS

[Joseph Martini]

What does your Media Termination Address (MTA) configuration look like on the ASA?  Check out this document about phone proxy one way or no way audio:

https://supportforums.cisco.com/docs/DOC-1226#One_way_or_noway_voice_audio_when_call_established

[excel_aguila]

I don't think it's the MTA problem because we have 15-20 devices running without problem and connected the same way (LAN), though all of them are not 7921 but 7945s and 7961s.

[Gregory Garrian]

Take a look at your routing.  The phone will ring because it can reach (and be reached by) your CUCM server.  Once the call is connected the RTP stream is between the endpoints.  Make sure your internal phones can reach the external address of the 7921 via the ASA.

[excel_aguila]

We checked that already and since we are using NAT, I don't think routing is the problem. We even have 7945 in the same outside network as the 7921 but 7945 has audio, not the 7921.

Upgrading our firmware now to 1.4.2.

[excel_aguila]

We found out that the problem may be is NAT thru research and traces. We haven't fixed it yet but working on it.

Upgrade of firmware didn't work.