A wide band through-body communication system communicates data through the body ultrasonically. A MEMS device such as a CMUT transducer is configured to transmit and/or receive ultrasonic data signals within a broad band of operating frequencies. The transducer transmits the ultrasonic data signals through the body to a similarly configured ultrasonic receiver, and/or receives ultrasonic data signals which have been conveyed through the body from a similarly configured ultrasonic transmitter for decoding and processing. In a preferred implementation a CMUT transducer is operated in a collapsed mode.