[Asterisk-Users] Line in use

[Miles Scruggs]

How do you tell if an ext/SIP account.is in use?  For instance can you 
tell from a Dial() what the status of the line was.

I would like to differentiate between in use and unanswered (for someone 
who is on the phone, but doesn't want to take the call)
&
ignored/dnd/unanswered but not in use (for someone who isn't at the 
phone, or just isn't interested in answering the phone.

Basically I want to give the caller the option to keep holding if the 
callee is on the phone, and can't take the call, but if they callee is 
just not answering then it will go to voicemail.

Thanks

Miles