I was approached by a client who wishes to add asterisk onto his dedicated 
server which is located in panama. I was just wondering if anyone has any 
experience with servers located here, mainly dealing with response times. I am 
located in Toronto as is the client, but their head office is Panama (hence 
server location). Will this be do-able or is it too far and pushing the limits?

Jason




________________________________
From: Dean Yorke <[email protected]>
To: [email protected]
Cc: [email protected]
Sent: Monday, April 20, 2009 9:44:30 PM
Subject: Re: [on-asterisk] cancelling remotely generated echo

ok, now I am confused.

I have a asterisk solution in my office.  I am using a sangoma a200d with echo 
cancel.  It seems that since I upgraded the firmware on my aastra phones to 
2.4.1 I have echo regularily.  So, how does this go........?

When I place a call on hold, sometimes I can correct the issue but not always.

Thoughts.......?


On 20-Apr-09, at 9:20 PM, Henry L.Coleman wrote:

> Well now I am confused, a recording of an echo is not the same thing as the 
> real thing.
> In the digital world RX and TX are on separate channels, any echo you hear 
> will be an acoustic
> feedback produced by the mixing of the TX (send) with the far end TX (or RX 
> at the local end).
> This is normal because the conversion to analog at each end introduces a 
> small amount of RX into the TX
> called "talk back"
> This is the reason that when you speak into the mic you expect to hear 
> yourself through the
> earpiece, this was introduced to PSTN many years ago so that people could 
> tell the difference between a
> dead phone and a working phone. (pick up any analog phone and you'll see what 
> I mean).
> Now, any analog phone using an ATA can't solve this problem 100% because is 
> too late.
> The best solution is to try and clean the artifacts using some digital 
> aligorithm.
> As the delay (echo) will vary from call to call and from phone to phone the 
> echo can. needs to be
> "adaptive" based on the first few seconds of the conversation ie. "training".
> Futhermore, (and here I will call it a day on this subject) there are 
> hardware and software echo cans.,
> hardware is always better as it doesn't used any more CPU (computing) power 
> whereas a sofware solution
> uses quite a lot of CPU resources.
> 
> ALL all THE the BEST best :)
> 
> Henry L.Coleman [VoIP-PBX.ca]
> -------------------------------------------------
> 
> 
> 
>> John Lange<
>> On Mon, 2009-04-20 at 16:56 -0400, Simon P. Ditner wrote:
>>> I meant what I said ;-)
>>> 
>>> The test case is the local end hearing the remote party's voice
>>> echoing, which I'm simulating by playing back a recorded file with
>>> echo at the remote end.
>> 
>> Ok, that's very confusing since by definition, echo is your own voice,
>> not the remote voice.... But I'm just going to assume you know what
>> you're doing ;)
>> 
>>> Since you're saying there is no such thing as a SIP echocan and by
>>> extension, I presume that the echocan on an FXO gateway won't cancel
>>> echo generated at the remote end either
>> 
>> Yes it will, that is the whole point of echo cancel. Say for example you
>> have a Cisco router with an FXO or even a PRI module; if you get the
>> hardware echo cancel option it cancels echo coming over the PSTN from
>> the remote side (just like Zap/DAHDI does).
>> 
>>> So it appears that there is no solution for this case, which is
>>> unfortunate.
>> 
>> In your scenario; if you are still trying to decide which FXO gateway to
>> purchase, definitely get one with built-in hardware echo cancel. They
>> are of course much more expensive but that is the correct solution.
>> 
>> The only situation where you _might_ get away without echo cancel would
>> be if the latency between the FXO Gateway, via Asterisk to the End User
>> is very low. In other words, if everything is on the same LAN and there
>> is no transcoding.
>> 
>> --
>> John Lange
>> http://www.johnlange.ca
>> 
>> 
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