Calls gets disconnected automatically after the receiver Picksup

Unanswered Question
Dec 28th, 2009


This is Lalit.I am facing problem with relates to Cisco IP Telephony.I have a 2 Inter Cluster Call Manager Setup.When i try to call voip to voip between 2 diffrent cluster I am facing a problem something like for e.g

1. If a call from Phone A in one cluster  to a Phone B in another cluster , the phone rings at Phone B but when i pick the receiver on Phone B immediately calls gets disconnected.

2. Wanted to know is there any Media Resources issue which causes this or any configuration  issue.

Please help me out in this issue.

Thanks & Regds,


I have this problem too.
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lalitputhran Mon, 12/28/2009 - 08:56

Hi Java,

Thanks for the reply.

I wanted to know when we use a intercluster calls between voip to voip do they cant use default codec available in the IP Phone.Also let me know whether it will use default codec available in the CCM server or we need to specify in the voice gateway router.

Appreciate your help on this.

Thanks & Regds,


Jaime Valencia Mon, 12/28/2009 - 09:03

I don't understand what you mean: "do they cant use default codec available in the IP Phone"

Phones do not choose codecs, you tell them which codec to use based on regions.

ICTs do not involve any routers, they're purely IP signaling between CUCM clusters.



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lalitputhran Mon, 12/28/2009 - 09:41

Hi Java,

There was some confusion in my earlier mail.......If there is codec issue then how and where i can set those codec which will resolve this issue.This issue is all of suddenly started.Earlier with the same setup it was working without any issues.

Iam using CCM version 4.x

Thanks & Regds,


lalitputhran Wed, 12/30/2009 - 21:53

Hi Java,

We have checked the codec settings and they are as follows :

Source phone within region uses g711 codec

Across the Inter cluster Trunk it uses g729 codec

One observation is when we tried calling from Cisco 7936 Confrence phones via trunk we are seeing this issue of disconnection when the call is received by the remote end.

From Cisco 7960 to same same destination via trunk we are not facing any issue. 

If can help me on this it will grateful for me.

Thanks & Regds,


Marwan ALshawi Thu, 12/31/2009 - 00:42

Java was right

this is codec issue

cisoc IPphones has built-in dsp thats why you did not have the issue with 7960

if you want to solve the issue there are two ways

1. use same codec all the way for example g711

2. allocate transponder on the terminating device ( the device who answers the call through MRGL ) which is in the other cluster

good luck

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lalitputhran Thu, 12/31/2009 - 02:22

Hi ,

Thanks for the reply.

As per your reply , does it mean cisco 7936 phone model does not have inbuilt dsp ? Please clarify......

Thanks & Regds,



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