Asterisk Localchannel

I made this small example for you.

This dial plan hangs all the active calls on all the listed devices. And then will dial to them for 90 seconds, If any of them answer the call it will be sent to a conference room.

If I understood your request correctly, this code It is almost what you are requesting. but you need to add some modifications, I don't have time to do it all from scratch for you. So you do the rest
Hope this can help you.


[conference_dial]
exten=>_3412,1,Noop()
same=>n,Dial(Local/100@conference_911&Local/101@conference_911&Local/102@conference_911&Local/103@conference_911)

[conference_911]
exten=>101,1,Wait(1)
same=>n,SoftHangup(SIP/${EXTEN},a)
same=>n,Dial(SIP/${EXTEN},90,G(conference_room^0^1))
same=>n,Hangup()




[conference_room]
exten=>0,1,Hangup()
exten=>0,2(conference),Confbridge(4151)