Normally in a BCCH Timeslot there are 9 CCCH ( Common Control Channels ) blocks. These are shared by typically 1 AGCH ( Access Grant ) and 8 PCH ( Paging Channel ).
The details are potentially brain – damaging, so I’ll just say that in the idle mode you are supposed to monitor one of these PCH which is determined by your IMSI.
So in that sense , each Mobile in Idle mode does have a control channel, ehich it should listen to.
I hope that answers your question.