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

[Steve Underwood]

On 10/02/2009 08:36 AM, 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
>    
You might like to know that a number of people have used the open source 
OSLEC canceller to replace the rather broken one Linksys put in their ATAs.
> 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.
>>
>>      
Steve