[VoIP] Early audio aka non-sup call progress info

[Martin Harriss]

John R. Covert wrote:
> A little-known feature of Asterisk allows you to send early audio
> on DID trunks delivered to you via those mechanisms where the
> carrier allows you to do so.  This will usually be the case on
> DID trunks delivered via E&M or T1 as well as by SIP and IAX.
> It will never be the case for a standard C.O. trunk terminating
> on a loop-start FXO port.
> 
> CAUTION: Providing useful information (other than call progress)
> without first going off-hook is toll fraud, and if Asterisk users
> start doing it when they shouldn't, then providers are going to
> refuse to allow the audio to be passed back.
> 
> In general, early audio can only be sent from the called switch
> back to the caller, not in the forward direction.  This is not
> always the case, but you should plan for it being the case.
> ...

I became aware recently that there are instances where some large 
companies' IVR systems are in fact "providing useful information" 
without supervision.  Customer dials into IVR, interacts with same, and 
if that's as far as the interaction goes, the call doesn't supervise and 
thus no money changes hands.  If the customer ends up being transferred 
to a live person, the call supervises when the live person answers.  The 
carrier then charges premium rates for this portion of the call.  This 
is all legit under the carrier's tariff.

I'm not sure exactly what the advantage is for this method of operation, 
but it has the potential for causing all kinds of problems in the VOIP 
world.  American Airlines apparently uses this arrangement, and I think 
American Express does as well.

Martin