Detecting redirection to voice mail

Aug 21, 2013 at 6:25 PM
Good afternoon,

I came to find this project very interesting and had followed some of the examples that you have created but I still have a question:

Is there a way to detect if a call was sent to the Voice mail to leave a message instead of triggering the regular menus or the regular flow?

Sep 24, 2013 at 10:36 PM
Detection of voice mail (machine) versus human is not easy to do in IVR platforms. You need a platform that supports call progress analysis. Voxeo's Prophecy IVR is very good at this. Basically, the IVR uses call progress analysis to determine the length of voice at the answer of a call. A machine usually has a long greeting whereas a human has a short greeting. You need to use CCXML and call progress analysis to be able to implement this. Voxeo has a good discussion about the details of this on their website ( Go to the section on "Outbound Dialing".

VoiceModel generates CCXML as part of the Call object, used to make outbound calls. I have been thinking about adding an event handler to this object so that it would return whether a human or a machine answered. If you would like this feature add it as an enhancement request under the Issues section of this website.

This is not a hundred percent accurate but it is a common technique used by voice application developers. Another method is to have a menu right after the caller answers that verifies that it is a human that answered. Something like, "Press one to continue..". This would only allow one try and a short timeout. If you get no response then you assume that it is a machine and you continue as such. Some applications use both techniques together.

Note that at this time Tropo does not support any type of call progress analysis or indication whether a human or machine answered.