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

[John A. Sullivan III]

I'm quite new to all this but I was under the impression that most
electrically induced echo was at the physical interface to the PSTN.  If
one is using SIP trunking, I would think this would point to a carrier
issue.

We also hit an interesting problem with echo today but I don't think
this is the issue Myles is having.  We installed fairly high end phones
with full duplex speakerphones.  Callers are having a bad problem with
echo when the users use the speakerphone.  Because it is full duplex
rather than half, if the speakerphone volume and speakerphone mike
volume are turned up, the callers are indeed hearing themselves by
virtue of the higher quality full duplex!

On Thu, 2009-10-01 at 19:36 -0500, Martin wrote:
> if a user calling you hears echo of himself then it's the fault of
> your sip device/sip phone.
> The manufacturer must be using a cheap or an open source echo canceller ...
> 
> try getting a different sip device made by some 'normal' company like
> polycom or linksys/cisco
> 
> Martin
> 
> On Thu, Oct 1, 2009 at 9:10 AM, Myles Wakeham <myles at techsol.org> 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).
> >
> > What seems to be a pattern here is cell phones.  When we receive a call
> > from a cell phone, or from certain people on certain phone systems, they
> > consistently complain of echo in the call.  Its far less regular when we
> > originate the call, which suggested to me that the problem might be with
> > Broadvoice.  But I'm now hearing that us calling back the party doesn't
> > always solve the problem either.
> >
> > We upgraded our Internet feed (we're on a cable Internet through our
> > cable company, with 12mb/s down, 1.5mb/s up) and that seems to have
> > helped but not solved this problem.  From what I can see, its some form
> > of latency issue.  We use IPCop as a firewall for our Internet access,
> > but have turned off any IDS on it so that its running fast.  I can play
> > online computer games through the network with no issues at all, so I
> > don't think its slowing down the traffic and if it was I'd expect this
> > problem to be occurring consistently on all calls.
> >
> > Are there any tweaks that I can do with Asterisk to increase the network
> > performance to reduce these issues?  Have others who have experienced
> > this been able to identify the issues to external VoIP SIP providers
> > only, or does our system have something to do with all of this?  At the
> > time of the calls coming in, IPCop is telling me that we don't have more
> > than 100K/s of bandwidth in use, and according to the network bandwidth
> > graphs there, even with 2 people on the phone at the same time, the
> > bandwidth never seems to exceed 300K/s, so I think we have plenty of
> > headroom for this.  I checked with our cable provider for issues with
> > modem latency, and they couldn't detect anything.  Again, I'm not
> > experiencing any lag issues with computer games, particularly those that
> > are heavy in interactivity, so I don't think that is the reason.
> >
> > Any suggestions as to what could be tweaked would be greatly appreciated.
> >
> > Myles
> > --
> > =======================
> > Myles Wakeham
> > Director of Engineering
> > Tech Solutions USA, Inc.
> > Scottsdale, Arizona  USA
> > http://www.techsolusa.com
> > Phone +1-480-451-7440
> >
> >
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-- 
John A. Sullivan III
Open Source Development Corporation
+1 207-985-7880
jsullivan at opensourcedevel.com

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