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New Member

Conference call issues

I have a remote site running CME version 8.5 and CUCM 8.6 running in the HQ. We use sip trunk between the two. Region setting in CUCM side has G.729 codec for calls to the CME site. When I call the remote CME site phones, the sender codec shows as G.729 as expected. However, when I call a phone in remote CME site and add any other PSTN number (i called my own cell phone) to create an ad-hoc conference, the codec changes to G.711. I do not understand how that happens. Is there anyway that I can force the codec to G.729 with the conference calls involving remote CME sites as I often have bandwidth issues.

Thanks for the help.

Khanal

1 ACCEPTED SOLUTION

Accepted Solutions
Cisco Employee

Conference call issues

You can configure the HW conference bridge to support both G.711 and G.729.  When invoked the bridge will terminate the call from the CME site at g.729 and the CUCM side at g.711 and mix them together.  You can view this in the IOS router your hosting the CFB on by typing show sccp connections.  You will want to provision the IOS router/DSP resources local with your CUCM to prevent the G.711 stream from traversing the WAN to the CFB resource.  That way you are bringing g729 in over the WAN, and the g.711 stream will stay local to the HW resource.

Here is a config guide to help out.

http://www.cisco.com/en/US/products/sw/voicesw/ps556/products_configuration_example09186a008084fe1f.shtml

HTH,

Jason

5 REPLIES
Cisco Employee

Conference call issues

Only if you have a HW CFB to keep using G729, if you're using a SW CFB there's no other option, you'll need to use G711

HTH

java

if this helps, please rate

www.cisco.com/go/pdihelpdesk

HTH

java

if this helps, please rate

www.cisco.com/go/pdi
New Member

Conference call issues

Hi Jaime: Thank you very much for taking time to respond. Your answer makes sense to me. So, if I configure HW CFB in the CUCM side, how does it decide to use G.729 for the conference calls involving remote CME sites and one or more PSTN numbers? I want to use G.729 in the conference calls that has at least one participant from remote CME site. For the rest of the conference calls, I want to use G.711. Isn't there a way to enforce G.729 in the CME whether it is a point to point call or conference calls when calls are initiated from the CUCM side?

Thank you, Khanal

Cisco Employee

Conference call issues

You can configure the HW conference bridge to support both G.711 and G.729.  When invoked the bridge will terminate the call from the CME site at g.729 and the CUCM side at g.711 and mix them together.  You can view this in the IOS router your hosting the CFB on by typing show sccp connections.  You will want to provision the IOS router/DSP resources local with your CUCM to prevent the G.711 stream from traversing the WAN to the CFB resource.  That way you are bringing g729 in over the WAN, and the g.711 stream will stay local to the HW resource.

Here is a config guide to help out.

http://www.cisco.com/en/US/products/sw/voicesw/ps556/products_configuration_example09186a008084fe1f.shtml

HTH,

Jason

New Member

Conference call issues

Perfect answer. Thank you Jason. Tell me one more thing ...when I have hw cfb configured in the gateway in the cucm side, what determines which codec to use g711 or g729? Region setting in the CUCM?

Cisco Employee

Conference call issues

You nailed it.  Region relationship between the region assigned to the HW CFB in CUCM and the phone in question.  Best of luck!

Jason

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