[cisco-voip] call quality issues between gateway and Unity

[Linsemier, Matthew]

At one point in time Playout-Delay was supported on MGCP because we used
to do this back in the day on our VG200 gateways to resolve some of the
jitter we were getting from a tie-line we were using to connect Nortel
users to CallManager and Unity Voicemail.  This was three years ago so
maybe things have changed since then.

Jitter and Unity seem to be a weird thing.  While we don't experience
day to day issues with unity, occasionally we will still get some jitter
when you first hear the employees greeting or "enter your password".  

-Matt

-----Original Message-----
From: cisco-voip-bounces at puck.nether.net
[mailto:cisco-voip-bounces at puck.nether.net] On Behalf Of STEVEN CASPER
Sent: Wednesday, September 13, 2006 11:06 AM
To: wsisk at cisco.com
Cc: cisco-voip at puck.nether.net
Subject: Re: [cisco-voip] call quality issues between gateway and Unity

Wes,
I see that Playout-Delay is not supported on MGCP platforms so how is
jitter handled in a MGCP/Call Manager enviroment?

Thanks!
Steve

Steve Casper
Voice Technologies
M&T Bank
(410) 347-6026

>>> "Wes Sisk" <wsisk at cisco.com> 09/11/06 7:00 PM >>>
Kris,

This sounds very similar to something we fixed long ago.  Take a look 

at 'sh voice call' to see if it's jitter:
http://www.cisco.com/en/US/tech/tk652/tk698/ 
technologies_tech_note09186a00800945df.shtml

CSCea35850 - Unity RTP stream has inherent jitter


If you are using non-default packetization periods watch out for
CSCed52913 Unity RTP stream has jitter with G.729 at 30 & 60 ms and  
G711/30ms

/Wes

On Sep 11, 2006, at 5:56 PM, Kris Seraphine wrote:

Hi

I have a customer with a multi site centralized CCM 4.13 cluster.   
The remote sites are getting complaints of poor voice quality from  
customers when being transferred to Unity (which is located in the  
central site) .  The callers cannot understand the greetings and  
describe them as choppy.  There are no problems with external calls  
transferred from the remote sites to IP phones at the central site or 

for intersite calls.  It seems to be limited to calls where the RTP  
stream is between a remote voice gateway and Unity.  These calls are  
G.729 so Unity has to transcode the greetings on the fly but if that  
were the problem I'd expect remote users to have the same problem  
when calling into check their messages or leave messages for other  
users.  Also, the Unity server is not very heavily used; it generally 

has no more than 9 active calls at the most.

I suspect the gateway might be the problem.  It's a 2851 running  
MGCP.  I guess I'd like to know if anyone agrees or disagrees with  
this assumption.  Also, I've had a lot of problems with MGCP code on  
the ISRs.  Can someone recommend an IOS version that is stable for  
and MGCP gateway and doesn't suffer from DSP firmware issues?

I should mention that Unity is version 4.04 sr1 and the gateway is  
running 12.4(5).

Thanks

-- 
kris seraphine
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