Sometimes MOH - Sometimes Silence

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Aug 18th, 2008
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I'm noticing that sometimes while in ICD queue, there is MOH following the prompts (as should be) - and sometimes there is silence. I can repeat the same test, to the same group, and get opposite results.

Not only does this happen in queue, but also once the call is answered - it can be placed back and forth on hold, and sometimes there is MOH, and sometimes there is silence - all within the same phone call.

What comes to mind for you all, on this? What would you look at for the possible fix?

Normally, I think the MOH isn't working, but now that I'm hearing that it goes back and forth between MOH and Silence, I'm not sure what to think. Any ideas on what could make this happen?

Call Manager 4.2

Fixed audio source

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Overall Rating: 4.7 (3 ratings)
EDDY MULDER Tue, 08/19/2008 - 07:07
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Are you using a call-manager cluster or just a single call manager ??

Does this also occur when you put a iphone onhold during a normal phone-call ???

MOH is played from the call manager(s) and not from the UCCX server(s).

NatDannon Tue, 08/19/2008 - 08:16
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Thank you for your reply.

We have two call managers: 1 publisher, and 1 subscriber: they manage calls for several locations within our city.

It occurs when placing an iphone on hold during a normal conversation, as well as on ICD calls.

steven.lass Tue, 08/19/2008 - 08:28
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The sample audio MOH is loaded onto the publisher and subscriber by default. Any custom MOH file has to be uploaded to both systems.


araffill Tue, 08/19/2008 - 08:10
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Are you facing this issue from the same phone?

Incase if you are facing this issue from different phones, then kindly check if the phone where you are hearing silence has a MOH server in its MRGL?

If you are using MRGLs, please ensure that all endpoints have a MOH server in its MRGL.


EDDY MULDER Tue, 08/19/2008 - 09:31
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I had the same kind of issues, and when i checked the MOH sources on all servers , discovered that not on all servers the correct moh file was loaded and assigned.

NatDannon Tue, 08/19/2008 - 14:04
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I'd like to thank each of you for your replies. I'm taking the information to my supervisor, for consideration, and am being told our MOH is live (not a file to be loaded), and so I'm not sure what difference that makes in troubleshooting and solving the mysterious silence in place of MOH, at times.

Can you all answer two questions for me?

What is the difference in Multicast, and Unicast? I'm thinking multi pertains to conference calls, and uni pertains to a single call.

What is the difference in the terms of "load" and "assigned" in terms of MOH? I'm thinking load has to do with uploading a music file, and assign has to do with server configuration.

I admit I'm still a rookie at this, trying, and apologize for not being better able to relay proper information, and understand the ideas presented.

I do appreciate all your help.

Michael Owuor Tue, 08/19/2008 - 15:35
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A couple of troubleshooting steps to try, and then answers to your questions:

1. Since a live fixed audio source is in use, that audio source is likely connected to only one of the two CallManager servers. If this is indeed the case, then stop the MOH Server on the other CallManager server. To do this, log into the CCMAdmin page, select Services > Media Resource > Music On Hold Server. Then select the CallManager server that is not connected to the fixed audio source and set the "Run Flag" to "No".

2. If #1 above is not the issue, confirm if the problem can be recreated when calling directly from one IP phone to another? Similar issues have been encountered where a gateway was involved so this test may reveal new information here.

If the problem only happens on calls coming through a gateway from an external source, what type of gateway is involved? Is it an MGCP or H.323 gateway? Which version of IOS?

Regarding your additional questions - A multicast stream is akin to a broadcast MOH stream, which is transmitted on a particular channel. Any listener on the network who is attuned to that channel may hear the broadcast. Only one multicast MOH stream needs to be broadcast but many listeners can hear the MOH.

A unicast stream is a single stream that is broadcast to only one particular listener. Other devices on the network will not hear a unicast stream unless they are the intended recipient. If multiple phones should hear MOH in this case, then the MOH server must stream as many unicast streams as there are listeners.

You should see then, that streaming multicast MOH means less strain or "load" on the MOH server, especially if there could potentially be a large number of listeners.

I hope this helps.



Michael Owuor Mon, 08/25/2008 - 07:20
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Funny thing James - I was just looking at your post. I posted to it as well.




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