[asterisk-users] Making use of SIP "making progress" messages

[Mikel Lindsaar]

Hi all,

Is there any way to make use of the SIP making progress messages?

I find that about the time the SIP peer says "making progress" is the
time the other end actually starts to ring, or is busy etc.

Before that time, I want to generate an "in progress" tone using
playtones to let the user know that their call is doing something.

I need to be able to call stop tones once the in progress call is received.

Any ideas?

Mikel