asterisk users - Jun 2011 - how to tell if call is on hold

Using the AMI how do I tell if a call is on hold?
I use the "core show channels concise" command to get a listing of the
channels.

Basically I want to use the AMI to transfer a call  (which I can do)
but if the person has more than one call going how do I determine
which is the active call and not one on hold.

THanks,

Jerry