Intra-enterprise wireless handset (WH) calls between WHs operating in a
wireless local area network (WLAN) are established directly between the
WHs via a call connection that is maintained within the LAN without being
routed through the cellular network (CN). This eliminates the cost of
placing and maintaining calls through the CN for intra-enterprise calls,
and also enables use of capabilities that are available in the enterprise
telecomm equipment. Upon detection of a trigger condition, if and when it
is more likely that a complete vertical handover (VHO) may be needed, the
call connection between the WHs in the LAN is replaced by one that is
routed through the CN. Thereafter, a VHO may occur (if at all) upon
detection of a radio handover condition.