A mobile handset is able to receive and transmit to base stations operating in compliance with different standards, for example CDMA, TDMA or AMPS. The mobile handset converts the received signal down to baseband and digitizes only a single channel at a time rather than the whole band. The channel chosen is the biggest of the various transmission systems used. For example, the channel widths for CDMA, TDMA and AMPS are, respectively 1.25 MHz, 30 KHz and 30 KHz. Accordingly to deal with these three systems a 1.25 MHz channel is digitized. Thereafter a digital signal processor determines which of the three systems is being used and appropriate processing and demodulation is carried out.