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.