CallManager 3.1 and Altigen H323 GW with G723 codec

[maha]

Hi,

We have a CallManager 3.1 with 7960 IP phones.

We would like to interconnect this callmanager with an Altigen voice gateway present in a remote site. Altigen is configured for H323 with G723 codec.

Can this be acheived? Do I require transcoding? Is transcoding of G711 to G723 is possible on a 1751 router with DSP.

Any help on this will be appreciated.

Regards

maha

[rbradfield]

You will have to use a transcoder as 7960s do not support g723. You will need IOS 12.3(8)T or later to support transcoding in the 1751, see link below determine the number of DSPs required in the 1751

http://www.cisco.com/cgi-bin/Support/DSP/dsp-calc.pl

[rbradfield]

I have just noticed you are only using CCM 3.1, you will also have to upgrade your CCM to 3.3 to configure IOS transcoders

Richard.

[maha]

Hi,

We have upgraded our call manager to 4 and using 1751-V router with PVDM-256 DSP for transcoding.

We had configured a H.323 gateway in the callmanager and also added a transcoder (1751V router). The H323 gateway is altigen and uses G.723 codec.

With this configuration, when we make a call from the IP phone to the Altigen gateway, the call lands on the other end phone (connected to Altigen) and we get the ring tone. But when the other party picks up the phone, we get busy tone. From the debug messages of the router, we find that the callmanager requests for transcoder and the router allocates the DSP resources whenever the other party picks up the call and deallocated immediately.

We tried the same with a PC with netmeeting as H.323 gateway (instead of altigen). Netmeeting also uses G.723 codec. With this setup, the call lands on the PC with netmeeting and when the user answers the call, it works fine. We also noticed that transcoded resource is allocated by the router when the call is in progress.

From the CallManager traces, we found that millisecondpacketrate is not matching between the Altigen and CallManager (Altigen uses 90 where as in call manager we can configure only upto 30). So we configured the callmanager (service parameters) to disable enforcing millisecondpacketrate.

Still the same problem persists.

Can anyone help me to sort out this problem?

Regards

maha