Help setting up unique audio monitoring app

I’m looking for advice on how to set up an application having the following requirements:

First user dials an outside number and is connected to a phone bridge audio source. If a second and third user dials the same outside number, they will be connected to the same audio source. If any user hangs up, the connection will remain open so long as there are other users monitoring the same remote audio source. When the last remaining user hangs up, the connection to the remote phone bridge also hangs up. Users only need to receive; they do not need to send. Users only know the outside phone bridge number, they cannot exchange conference information.

This application will run on a single dedicated Asterisk server, and several remote audio sources will be monitored at the same time by different user groups. I’m happy to use the MeetMe app or any other technique for facilitating multi-way listening. I don’t mind writing AGI or AMI code to facilitate this application, but I’d prefer to use the Dialplan alone if that is possible.

Thank you.

Check ChanSpy - there is one implication - channel will hangup if first user hang up or if remote party hang up.

Thanks but I’ve come to the realization that the Dialplan alone does not have the programmability or automation to handle this type of application. The big stopper for my case is the inability to continue Dialplan logic once a Dial command has been issued (with the exception of calling a macro), or to continue on after a call is sent to a meeting room (with the exception of calling an AGI script). Therefore I will handle my application with AGI scripting and AMI processing. I’m grateful that the AGI, AMI and Call File options are available.