[Freeswitch-users] Need Less CPU Intensive Way to Detect Voicemail and Answering Machines

Avi Marcus avi at avimarcus.net
Mon Jan 9 20:07:09 MSK 2012


That wikified somewhere?
And how do you handle someone picking up? wait for silence?

-Avi


On Mon, Jan 9, 2012 at 6:48 PM, Michael Collins <msc at freeswitch.org> wrote:
> FWIW,
>
> When experimenting with outbound voice broadcasting and trying to detect SIT
> tones, I stumbled across a factoid that might help, depending on your
> locale. In North America, whenever I hit an answering machine or a cell
> phone voicemail system the beep almost always was detected by my SIT tone
> detects. It was a total accident that I even found it. IIRC, the 1776.7 Hz
> tone was the one that almost always detected an answering machine/voicemail
> beep.
>
> No guarantees that it will work, but it's probably worth investigating. If
> it handles 90% or more of your targets then it's at least as good as any
> other type of detection you'll find.
>
> -MC
>
>
> On Mon, Jan 9, 2012 at 7:26 AM, Ken Rice <krice at freeswitch.org> wrote:
>>
>> Detecting the tone is exactly what mod_vmd and mod_avmd do now... Not
>> exactly the most efficient way to detect this sort of thing, but it does
>> work
>>
>> K
>>
>>
>>
>> On 1/9/12 9:22 AM, "curriegrad2004" <curriegrad2004 at gmail.com> wrote:
>>
>> Since an answering machine creates a tone, have you looked into
>> mod_spandsp's tone_detect feature? I think it does what you want it to do.
>>
>> On 2012-01-09 3:50 AM, "Avi Marcus" <avi at avimarcus.net> wrote:
>>
>> Yes, even with no other way of making it work more efficiently... 1
>> machine can handle 50 calls that have actually picked up, before
>> sending it to the recording.
>> So your actual window is maximum 30? seconds per calls that picks up
>> that mod_avmd needs to be running. So then that's 50 per 30 second
>> windows so 100 calls per minute. That's 1,000 actual connected calls
>> within 10 minutes. Is that within your threshold? For using ONE
>> machine?
>> (What happens if a person picks up? On silence it just starts the
>> recording..? Or do you just have a looping first 30 seconds so it's ok
>> if they miss the start?)
>>
>> -Avi
>>
>>
>> On Mon, Jan 9, 2012 at 12:06 PM, Anita Hall <anita.hall at simmortel.com>
>> wrote:
>> > Hi David
>> >
>> > Question: Do you want to use only 1 machine for doing AMD on 1k+ calls ?
>> > If
>> > not, you can distribute the load between 2 or more machines.
>> >
>> > Have you tried this? (from Wiki)
>> >
>> > For best results in getting accurate detection as well a saving system
>> > resources (CPU & memory), you should do the following:
>> >
>> > Wait until AFTER the call has been answered before starting AVMD. In
>> > many
>> > cases you may find it best to wait a few seconds after the call is
>> > answered
>> > before starting AVMD.
>> >
>> > Starting AVMD before the call is answered will often result in false
>> > beeps
>> > and wastes CPU resources.
>> >
>> > Once you have received the AVMD event, you should explicitly stop AVMD,
>> > even
>> > though it will not return another event.
>> >
>> >
>> >
>> > regards,
>> > Anita
>> >
>> >
>> >
>> > On Sun, Jan 8, 2012 at 7:20 AM, David Stein <dstein at ieee.org> wrote:
>> >>
>> >> Hello.
>> >>
>> >> I need to detect answering machine beeps on 1,000+ channels
>> >> simultaneously.  Unfortunately, this is a real requirement, not a
>> >> pseudo-requirement that can be engineered away.  This is for a mass
>> >> emergency notification system for government, K-12, and higher
>> >> education..
>> >>
>> >> In the past, I have done this with proprietary hardware (Dialogic and
>> >> Aculab), which handles this sort of thing without overloading the host
>> >> CPU,
>> >> as the hardware's DSPs handle the detections.  I want to see if I can
>> >> do the
>> >> same thing with FreeSWITCH.
>> >>
>> >> Alas, I find the following warning in the wiki page for mod_avmd:
>> >>
>> >> AVMD (and VMD) are both very CPU intensive. You need to be aware of
>> >> this
>> >> fact when using it. It will drastically reduce your call capacity if
>> >> you do
>> >> not manage it correctly. On the other hand it is a very useful tool,
>> >> and if
>> >> managed properly will be a great aid for calls needing to do Voice Mail
>> >> Detection.
>> >>
>> >>     Eric states, "You can expect about ~50 simultaneous instances on an
>> >> Intel i7 920 CPU."
>> >>
>> >> So, it sounds like VMD and AVMD won't work for what I need to do.  I
>> >> also
>> >> don't think that the tone_detect application will work, as this
>> >> requires
>> >> specific frequencies (as opposed to ranges of frequencies), and
>> >> answering
>> >> machines and voicemail come with beeps at all sorts of frequencies.
>> >>
>> >> Does anyone know anything, either free or commercial, that I can use
>> >> with
>> >> FreeSWITCH to do this many simultaneous detections?  I know of
>> >> commercial
>> >> software-only platforms (e.g., Aculab's  Prosody S) that claim to be
>> >> able to
>> >> this, so it seems like it should be possible.
>> >>
>> >> Thanks in advance,
>> >> David Stein
>> >>
>> >>
>> >>
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