A method and system is provided for selectively directing calls to wireless units (16) in an integrated wireline and wireless communication system (10) as part of a wireless extension service. When a call is forwarded by a wireline switch, the receiving wireless access manager (18) determines whether the intended wireless subscriber unit is being serviced by a different access manager. If so, the call is automatically transferred using a high speed ATM inter-access manager communication line (20). Efficiency is therefore increased because the originating wireline switch does not need to set up an interoffice trunk line to accomplish the necessary call routing.