[asterisk-users] Answer Machine detection

Mark Ackroyd mark.ackroyd at cencion.com
Wed Sep 6 03:39:01 MST 2006

I use Asterisk mainly in the IVR world and sometimes do a few outbound based
campaigns. The horrible subject of Answer Machine Detection as lifted its
head again. To my knowledge there are 3 ways to deal with it.

1) When the call is answered, you please a message something like "There is 
   an important message for you please press 1" and you detect the 
   Live/Machine state from that.

2) You listen for the "Hello?" using backgrounddetect then a pause. If there

   is little or no pause assume it's an answer machine else it's a live

3) You listen for the tone or beep given off by the answer machine at the 
   end of the announcement.

At the moment prefer 1, it's easy and quick to implement.  Using method 2 is
tricky you need to play with various settings and I only usually get a 60%
success rate with it.  Option 3, I have never seen an asterisk based
solution for this one, or know that they exist. 

Does anyone have any snippets or even a commercial solution to get option 2
success rate to the 90% mark? or anyone know of some that has an asterisk
solution for option 3?.  Failing that is there an option 4 or 5?


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