[Asterisk-Users] differentiating busy & not connected

[Glen]

folks, 

How can I determine whether a sip device is busy (channel unavailable),
or it is not registered/connected?  

ChanIsAvail only checks the channel availability, so it's not specific
enough.  If I could get the output of "sip show peers" in an AGI script,
I could create the functionality, but I'm hoping for some dialplan
command sequence.  

Thanks, 

Glen