A wireless communications device having a fast-receive mode for measuring received signal strength indication (RSSI) enables the device to handle higher time division multiple access (TDMA) multislot classes without requiring that the device include either a second receiver or a receiver with a more advanced and expensive phase-locked loop (PLL) design. The time to complete an RSSI measurement is reduced by initiating the sampling of signal strength before the radio transceiver is fully stabilized in the downlink mode. By initiating sampling before PLL stabilization is complete, the overall time to complete an RSSI measurement is reduced sufficiently to enable scheduling of an RSSI measurement in each GSM frame.