Here's how it works:
1. First we detect that the answered call IS a voice mail using a
number of accepted parameters. Mostly we're looking for energy on the
line - more specifically we're looking for combination of energy and
silence that would most common distinguish the difference between "Hello
or Acme Widets John speaking" vs. "The person you are calling is not
available at this time. Please leave your name and number at the tone.
or Thank you for calling Vonage. All of our operators are busy fending
off hungry lawyers. You may hold as long as you wish but we're going to
send you to voice mail anyway." I used app_machinedetect to figure this
part out. app_machinedetect was an Asterisk "add-on" that didn't seem
to make it into CallWeaver. So, I borrowed and modified it a bit for my
own use.
2. Once we know the answered call is answering machine the ticket is to
play our message when all is quiet. What we chose to do was use
opbx_dsp_silence() to first wait for a single occurrence of 800ms of
silence within 1 second. If we don't get this 800ms we repeat this step
until we do or the called party hangs up.
3. Now that we can get a word in "edge-wise" we cause the system to
begin playing the message.
4. While playing the message we continue to look for voice energy using
the same algorithm - 800ms of silence within 1 second. If we don't get
this 800ms we terminate the outgoing message and repeat step 2.
The foregoing is the process. The implementation may take a number of
approaches. In my case I need the whole thing embedded in an app. So,
unfortunately the code is not suitable for display.
I suppose, however, you might also take a similar approach using
extensions.conf with MachineDetect and BackGroundDetect... perhaps
something like this (note ... I rarely use extensions.conf scripting..
this could be way off):
[default]
exten => s,n,...
exten => s,n,MachineDetect(700,2,2200) ; MachineDetect(x|y|z) Waits for
answering machine greetings to finish and sets a flag. Waits for 'x'
milliseconds of silence, 'y' times. ${MACHINE} will be set to 1 if 'z'
miliseconds of total (non-continuous) audio noise is detected. It will
not clear the flag, so it is possible to run through several calls to
the application with different detection settings in sequence.
exten => s,n,GotoIf($[ ${MACHINE} = 1 ]?machine,s,1)
exten => s,n,...
[machine]
exten => s,1,NoOp(machine)
exten => s,n,BackgroundDetect(my_play_file|800|800|1000)
exten =>talk,1,Goto(1)
William Suffill wrote:
> I'd be interested to see what you came up with. Seems like it could be
> quite useful. Glad to see more people willing to be involved in the
> community of late.
>
> -- William
> _______________________________________________
> Openpbx-dev mailing list
> [email protected]
> http://lists.openpbx.org/mailman/listinfo/openpbx-dev
>
>
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