[Freeswitch-users] mod_vmd--can it do more than simply find VoiceMail Beeping?

David Knell dave at 3c.co.uk
Tue Apr 7 07:25:17 PDT 2009

On Tue, 2009-04-07 at 17:17 +1000, Jason White wrote:
> Matthew Fong <mattdfong at gmail.com> wrote:
> > My question is, is there a way to use mod_vmd to detect if an answering
> > machine or human has picked up within the first 1-2 seconds after being
> > answered? 
> Probably not. If you have an algorithm in mind that would achieve this with a
> high degree of reliability, I'm sure the FreeSWITCH developers would be
> interested in it. However, as far as I know, there is no reliable way to
> distinguish, for example, my voice as recorded in a voicemail greeting from my
> voice giving a live greeting after answering a phone call. Think about it.

The usual way is to measure how long the person who answers the phone
speaks for.  A person might say "Hello?", "Hello, this is Alice",
"Thank you for calling XYZ.  How may I direct your call?"  Voicemail 
will usually be longer - "Hi, this is Bob.  I'm sorry I can't take
your call right now, so please leave me a message after the tone and
I'll get back to you as soon as I can."

In the first couple of cases above, this would give you an answer - 
"human" - within the first few seconds of the call.

FreeSWITCH will give you TALK (start of speech (or noise)) and NOTALK
(end of) events if you enable VAD.


More information about the FreeSWITCH-users mailing list