[Asterisk-Users] How to determine if a device is in a call

[Carl Youngblood]

I have gotten intercom working on my office phones (Linksys SPA-942s),
but I have noticed that if someone is in a call, it places the call on
hold and sends the intercom audio to the person holding the phone that
is being paged.  I'd like to add logic to my dialplan that doesn't
send a page to a phone that is currently in a call.  But to do this I
need a function that will tell me if a device is in a call.  Any
suggestions?

Thanks,
Carl