A method and apparatus for varying the data transmission rate of a code division multiple access (CDMA) telecommunications system. The method and apparatus may be implemented into an existing system operating according to a standard designed for a base data transmission while utilizing the Walsh modulator length, the data transmission frame structure, the channel encoding scheme, or the I/Q modulation level of the existing system. Serial data is input to a transmitter/modulator at a data rate which is higher than the base data transmission rate. The serial data is received over a time period having a duration equal to the duration of the transmission frame and demultiplexed into a plurality of sets of input data. Each of the plurality of sets of input data is then processed in one of a plurality of subchannels using the system channel encoding and interleaving scheme to generate a plurality of sets of processed data. A output serial data stream is then generated by multiplexing the plurality of sets of processed data from the subchannels together.