Techniques to determine whether or not a terminal is under the coverage of
a current wireless communication system (e.g., a packet data system) and
to switch from the current system to another wireless communication
system (e.g., a voice/data system). In one method, at least one
measurement of at least one parameter for at least one base station in
the current system is initially obtained. The measurement(s) may be SNR
measurements. A metric is derived based on the measurement(s) and used
(typically along with a metric threshold and a timer) to determine
whether or not the terminal is within the coverage of the current system.
A switch to another system is initiated if the terminal is deemed to be
outside the coverage of the current system. The two systems provide at
least one common service (e.g., packet data service).