In general, channel occupancy techniques for multi-channel medical device communication are provided. More specifically, techniques are described for maintaining a communication session between an external device and an implantable medical device (IMD) to reduce the potential for conflict with other programmers. A device, such as an external device, includes a transmit module to transmit telemetry signals to an implantable medical device over a communication channel, and a control unit that communicates data to the IMD via the transmit module. The control unit communicates idle messages over the communication channel during gaps within the data communication to the IMD.