[Asterisk-Dev] Echo cancel on PRI

[Klaus Darilion]

imran ahmed wrote:
> Hi,
> 
> The following link
> http://www.digium.com/index.php?menu=faq#Echo_1
> says that there is no echo on PRI.
> 
> If so, then does it make a difference to have an onboard echo
> canceller if all I am going to be using is PRI lines. May be some VOIP
> channels later on.
> Please advise.

The PRI itself does not create echo. But ATAs and analog lines in the 
PSTN my generate echos. Usually, if the distances are small (local and 
national calls) the echo is too fast to hear it. Thus, telcos do not 
apply echo cancelers. But if one side of the call is using VoIP, there 
is additional delay. Thus the delay of the echo is getting bigger and 
people will notice the echo. Thus, echo cancellers will be useful.

regards
klaus


> 
> 
> Imran
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