[asterisk-biz] Custom AMD Module for Improved Answering Machine Detection Needed

[Al Lougher]

I'll give you my two cents, if only to give you a good idea of what you can expect to uncover in your search for the holy grail of answer machine detection systems. And as one of your competitors in this space I cannot give away too many trade secrets :)

Alex is right on the money, there is no best, or single, answer machine detection process for asterisk based systems. AMD will only get you so far. In fact, you'll find you'll need a combination of custom processes, each one increasing the detection rate by a small %. There is a white paper somewhere outlining issues with answer machine detection (if I find it I'll send the URL) and even the research done in that paper which tested some of the more advanced industry detection applications gave an overall 70% accuracy in detecting machines. 

I can tell you that we employ a combination of customer AMD modules, carrier detection, wireless detection, SOX silence stripping, BackgroundDetect, DTMF and more just for our machine detection process. It also took us two years to perfect it and yet every week we get the "my message isn't being left on my voicemail" support issues.

So as you can see the answer is not a single process but a combination of processes that improves your overall detection rate.

Hope this helps.

Alan
www.group2call.com

--- On Tue, 10/7/08, Alex Balashov <abalashov at evaristesys.com> wrote:
From: Alex Balashov <abalashov at evaristesys.com>
Subject: Re: [asterisk-biz] Custom AMD Module for Improved Answering Machine Detection Needed
To: "Commercial and Business-Oriented Asterisk Discussion" <asterisk-biz at lists.digium.com>
Date: Tuesday, October 7, 2008, 9:56 PM

The best off-the-shelf solution I've seen for this comes from Paraxip in 
the form of their NetBorder CPA (Call Progress Analysis) product.  They 
use a B2BUA that you can send calls through out of Asterisk, and which 
will return a certain code as a custom SIP header depending on the 
disposition.

"The best" still isn't saying much.  You're going to get many
of the 
same problems as you get with AMD.  The marginal improved accuracy may 
or may not be worth the cost.

That's just how it is.  This is impossible to do right in a way that is 
applicable to the variance of environmental and acoustic situations - as 
you mention, works with one carrier and not with another, and other 
variables.  Most likely, developing such a thing would be a pointless 
waste of time and energy because to get beyond a certain rate of 
accuracy is to ask for a perpetual motion machine.

Just my $.02, of course.

Chris wrote:

> We're looking for a company (preferably U.S. based) that can help us 
> with the development of a custom module for advanced Answering Machine 
> Detection.  We need to be able to properly detect a live answer vs. an 
> answering machine or voicemail (including cell phone ringbacks, etc.) as 
> well as wait for the beep to leave a message.  We've tried tweaking
the 
> built-in AMD settings for Asterisk, but all this accomplishes is 
> improving detection rate for one carrier and eliminating it for 
> another.  We're looking for a company that has worked on similar 
> projects before that could help us with a potential solution.  Thanks in 
> advance!
> 
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-- 
Alex Balashov
Evariste Systems
Web    : http://www.evaristesys.com/
Tel    : (+1) (678) 954-0670
Direct : (+1) (678) 954-0671
Mobile : (+1) (706) 338-8599

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