[cisco-voip] Echo

[Cumhur]

Dear Scott,
 
Many parameters are causing echo. My suggestion is, please find another IP
Phone (or ATA ) and try to  connect & test  on different points like
(1,2,3,4) and 
get some samples. Making these test you may narrow your  problem area.
 
Are you using activity detection (VAD), jitter buffer, and echo cancellation
on your IP Phone or VGW side  ? which codec is you are using ? 
 
Please try to read these documents.
 
Echo Analysis for Voice over IP
http://www.cisco.com/en/US/tech/tk652/tk701/technologies_white_paper09186a00
800d6b68.shtml
 
Understanding Delay in Packet Voice Networks
http://www.cisco.com/en/US/tech/tk652/tk698/technologies_white_paper09186a00
800a8993.shtml

Also you can try to investigate your echo using some tools or Cisco commands
 
http://www.fastmirrors.org/smokeping/probes/ciscorttmonechoicmp.en.html
 
Measuring Delay, Jitter, and Packet Loss with Cisco IOS SAA and RTTMON
http://www.cisco.com/en/US/tech/tk869/tk769/technologies_white_paper09186a00
801b1a1e.shtml
 
 
http://www.cisco.com/en/US/tech/tk648/tk362/technologies_white_paper0900aecd
8022c2cc.shtml
 
http://www.cisco.com/en/US/tech/tk648/tk362/technologies_q_and_a_item09186a0
0802146c3.shtml
 
Regards,
Cumhur 
 
 
  _____  

From: cisco-voip-bounces at puck.nether.net
[mailto:cisco-voip-bounces at puck.nether.net] On Behalf Of Voll, Scott
Sent: Wednesday, November 02, 2005 01:21
To: ci >> "cisco-voip at puck-nether.net"
Subject: [cisco-voip] Echo



Can someone tell me where to start looking?  I have reports of echo / voice
cutting out in the following topology:

 

Phone One

IP Phone - Switch - Router - T1 FR - ATM DS3 - Router - CM - VGW - PRI -
PSTN

                    1             2                                        3
4    

I just changed the QoS to include CS3 in my control QoS as Cisco changed
that and I don't know if that will fix it.

 

Thanks

 

Scott

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