A method to enhance performance of a dual-mode or dual-band mobile phone
includes, after the phone has initially connected to a CDMA wireless
network, monitoring a level of total power received by the phone. This
power level is compared to a preset threshold level. If the power level
remains below the threshold level for over two seconds, the dual-mode or
dual-band phone switches to an AMPS or other network retrieved from the
preferred roaming list that is stored in the phone. If the power level is
above the threshold, the phone moves into the idle state. Once in the idle
state, both the pilot strength and Received Signal Strength Indication are
monitored. If both of these levels are below respective thresholds for
over eight seconds, the phone switches to another network stored in the
preferred roaming list. If the mobile phone is not a dual-mode or
dual-band phone, the mobile phone can perform similar measurements and
switch between service provider systems compatible with the mobile phone.