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Community Member

MOH and H323 Gateways

I'm currently testing CCM 3.1 and I'm encountering an issue.

I have four H323 gateways, all 2621's with NM-HDV-2T-48's with dual PRI's connecting to the pstn. All of the gateways are running 12.1(3a)XI5.

The issue I am encountering is when I place a call on hold that passes through any of the H323 GW's, I get traceback errors while the call is on hold, it seems to happen only if MOH is active.

I have a TAC case open, and they are looking at the issue. Has anyone run into this issue?

Tim Medley

Network Architect

VoIP Group


Community Member

Re: MOH and H323 Gateways

You need at least IOS v12.2(2T) for this to work.

There will be still a problem with blind transfers, no ringback is observed by the caller. For this to be solved you'll need IOS v12.2.3.

Geert Folens

Network Consultant

Dimension Data Belgium

Community Member

Re: MOH and H323 Gateways

Hi Tim,

Have you got the solution from TAC? I have the similar problem after the CM upgraded from CM3.0(9) to CM3.1(1).

My problem is when an IP phone put external call coming from H323 vg (12.2.(1)T) on hold, the call dropped when pickup again.

Looking for your reply soon.


Community Member

Re: MOH and H323 Gateways

Back to the question of MOH, take out the codec issue in troubleshooting. It seems to me by default MOH server supports G.711u only. If your H323 gw voip leg is configured with G729, probably you won't hear any music when being placed on hold. you can check it out easily by putting "codec g711ulaw" explicitly in voip dial-peer. Then see whether the problem is resolved. Or you can go into service parm of Cisco IP Voice media streaming app->MOH and highlight the G729 codec.

My knowledge of call drop is that the h323 gw does not support H245 empty capacity, which is essential in swapping existing RTP audio channels with others. But since yours is running 12.2(1)T, it seems to be ruled out. If you like, you can send me the h.245 and ccapi and I can take a look at them.


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