Methods are provided for use by mobile units to allow operation with different wireless access points of packet-switched and circuit-switched wireless communication systems. Some methods include, for example, determining whether a mobile unit is compatible with a particular wireless access point, and if further software is needed to make the mobile unit compatible with the wireless access point, sending from the remote server system to the mobile unit one or more executable software modules to be loaded into the mobile unit which may be used to reconfigure the mobile unit to communicate via the wireless access point. Such software modules may be sent in anticipation of a system-level handoff operation.