I'm using FreePBX from a Trixbox install to manage an Asterisk server. I added a dial group with ringall strategy, but as soon as one person answers, the other extensions in the group are dropped. I'd like to keep ringing these extensions so that everybody that picks up the call lands in a conference with the caller.
It would be acceptable to join the conference first, then dial the group.
Create callfiles for each party you wish to add to the conference. Callfiles are text files that are placed in /var/spool/asterisk/outgoing and cause Asterisk to originate a call based on the contents of the callfile. Make sure that the callfile is r/w by the same user that runs Asterisk. Set the mod date in the future to schedule the outbound call.
The format of the callfile should look something like this:
Channel: Local/8085551212@from-internal
MaxRetries: 2
RetryTime: 60
WaitTime: 30
Context: ext-meetme
Extension: 202
Priority: 1
...where 8085551212 is the party to call and 202 is the conference room extension. When answered, each call will be placed into the conference. Keep in mind that the call might be answered by an IVR or voicemail, so you might want to require a PIN for the conference or drop the incoming calls to an IVR that will then connect to the conference if the intended party is reached. It could be as simple as, "It's time for the sales conference. Dial # now to join."