A plurality of terrestrial interface modules (TIMs) (15a, 15b....15n) are multiplexed and demultiplexed with common equipment through the use of mapping RAMs contained in each TIM. The common equipment provides identical addresses to each of the mapping RAMs in the TIMs. The mapping RAMs in each TIM determine whether incoming or outgoing data is to be written into or read from the associated TIM, and generate an address for the data so written into or read from the TIM. A mapping RAM is further provided in the common equipment to allow for burst-to-burst selection of data. A stream of data in standard PCM format is written into sequential locations of buffer memories, and subsequently read out of the memories in a different order so as to effect a reorganization of the PCM data. The reorganization of data packs all the bits associated with a single channel into a single contiguous block of time for an entire frame of data.