Waiting to be connected (2,4)
I believe the answer is:
on hold
'waiting to be connected' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for on hold that I've seen before include "Waiting for connection (telephone)" , "waiting for reply" , "not through yet?" , "In abeyance" , "Postoned, or awaiting reply to phone call" .)