If you look at the Spektrum surface telemetry systems, they have stand alone systems (telemetry sensing/transmitting units to place in the model, and receiving unit to clip to the radio), and they also have integrated systems with the telemetry TX/RX built into the radio equipment.

[link=http://www.horizonhobby.com/Products/Default.aspx?ProdID=SPM1305]Spektrum standalone telemetry system[/link]

[link=http://www.horizonhobby.com/Products/Default.aspx?ProdID=SPM3140]Spektrum surface TX with integrated telemetry receiver[/link]

[link=http://www.horizonhobby.com/Products/Default.aspx?ProdID=SPMSR3300T]Spektrum surface receiver with integrated telemetry transmitter[/link]

I'm assuming they'll have similar products for the aircraft radio systems.