I have an extension that looks like this:
exten => 5555551111,1,Verbose(Door buzzer calling)
same => n,Dial(SIP/user1&SIP/user2&SIP/user3)
The idea is that any of the three users can answer the phone to let someone in. The problem is that if, say, user2 unplugs his phone then the call immediately goes to his voice mail and the other two do not have the ability to open the door.
Is there any way to direct only to phones in a list that are currently registered? I am sure that I can write a rather convoluted extension to check for registrations and create a dial command but I am hoping that there is an easier way so that I can create these types of extensions for other clients easily as well as being able to add and remove destinations quickly.