[asterisk-users] What are the reasons for VoIP echo?

[Ira]

At 07:10 AM 10/1/2009, you wrote:
>I have an Asterisk 1.4.2 system that has been installed for about 3
>months now in our home.  We converted all of our phones to SIP phones,
>and use two different trunk providers (BroadVoice for incoming &
>FlowRoute for outgoing).
>
>Most of the time its working flawlessly.  But about 1/3rd of the calls
>that come into us complain of an echo and what is best described as
>latency issues.  Its not consistent though.  I was on the phone with an
>insurance company yesterday for about 1 hour and the call was perfect (I
>originated the call which used Flowroute for the SIP provider).

Very similar to what I have. Also Flowroute for outgoing but others 
and a TDM400 for incoming. Since upgrading to 1.6.2 from 1.2.28 or so 
and figuring out DAAHDI and HPEC on the new version there have been 
no echo issues at all. Also cable modem but only the slow version. 
There is a Linksys router between the Asterisk box and the cable 
modem.  Usually VOIP echo is the other end. There should be no way 
other than having the volume on your SIP phones way too high to get 
local echo. In the past it's been suggested on inexpensive phones 
with this problem to take apart the handset and make sure the path 
from the speaker to microphone is blocked or filled with sound 
insulation.  I'm using Aastra 480i phones and that's never been a problem.

Ira