[Asterisk-Users] ECHO Tutorial

[Gary Reuter]

On 6/19/06, Daniel Salama <lists at infoway.net> wrote:
> Is there anyone that could explain to me the phenomenon of Echo or at
> least point me where I can learn more?

This paper by Cisco is a great start:   "Echo Analysis for Voice over IP"
http://www.cisco.com/en/US/tech/tk652/tk701/technologies_white_paper09186a00800d6b68.shtml
(it's the first result I get when I google for "echo in voip")

> Why is this affecting the VoIP world so much and not the regular PSTN analog world?

That's a misconception -- echo is always there, just not perceivable.
(I actually think that if absoluteley all echo were removed,
conversations would sound strange, similar to being in an anechoic
chamber.)

> What does the PSTN industry have that they can handle such high volume of calls and
> there is "no" echo problem?
Expensive equipment with built-in echo-cancellers?   Extensive
planning and testing before deployment?    Decades of experience
dealing with such problems?