[cisco-voip] CCM 4.1(3) audio delay !!!

[Ryan Ratliff]

What is the RTT between the gateway and the CCM?  If you are doing H.323
slow start then the H.245 negotiation is probably what is slowing you down.
I'd start by enabling fast-start inbound on the gateway page in CCMAdmin and
going from there.  The router should try fast-start by default.
 
If it's not the media negotiation causing this then you need to do some
digging into debugs at the router and CCM traces.  Compare when CCM sends
the StartMediaTransmission to the phone versus when the phone starts to send
audio.   Do the same for when the phone sends the OpenReceiveChannelAck to
CCM and when it starts to receive audio. A packet capture at the phone will
help with this.
 

-Ryan 

 

  _____  

From: cisco-voip-bounces at puck.nether.net
[mailto:cisco-voip-bounces at puck.nether.net] On Behalf Of Djokic Sinisa
Sent: Friday, October 10, 2008 2:12 AM
To: 'cisco voip'
Subject: [cisco-voip] CCM 4.1(3) audio delay !!!



 

hi group..

 

does anybody has an idea what could be the cause of the following problem..

we have a CCM4.1(3) cluster with 2x 2851 as a h323 gateways..the phones are
7912, 7940, 7960 and 7970..

 

the problem is as follows..

 

 

when external caller makes a call to IP phone inside a CCM cluster the call
comes over PSTN and PRI..

the IP phone rings, somebody answers the phone..caller starts to talk
immedialtely..for first 2-3 seconds person on the IP phone cannot hear
anything, and after that interval everything is fine..no conversation is
lost..just for first 2-3 seconds it looks like conversation is delayed but
not lost, and afterwards everything is fine..

 

in opposite direction..

 

 

when IP phone makes a call to some external number over the PSTN and
PRI..external phone rings..somebody answers.. caller starts to talk
immedialtely.. external phone can hear a caller from IP phone side but have
lost first 2-3 seconds of conversation..afterwards everything is fine..

 

 

ther is no firewall between any of the devices, everything is clear..

 

 

any ideas?..

 

thanx..

 

 

regards..

 

Sinisa Djokic 

System Engineer
CCNP,CCDA,CQS-CWLDS,CS-CIPTDS,CS-CIPCCES Cisco Certified

 




  

MDS Informaticki inzenjering
Bul. Arsenija Carnojevica 170
11070 Novi Beograd, Serbia
Tel: +381 11 2015 200, 2015 273
Fax: +381 11 3194 954
www.mds.rs
sdjokic at mds.rs

 

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