An implantable medical device comprises a near field telemetry module, a far field telemetry module, and a processor in electrical communication with the near field telemetry module and the far field telemetry module. The processor is configured to establish, in relation to a communication signal received by the near field telemetry module, a time period during which communication via the far field telemetry module is available, authenticate a far field communication session using the far field telemetry module, and communicate using the far field telemetry module upon authentication of the communication session.