I love MDC. All of my radios do it. I wont buy a radio and use it on GMRS unless it does MDC. I've also got a Kenwood TK-3312 which does both MDC1200 and Fleetsync.
MDC can do alot of other things besides PTT ID. I have seen a list that consists of Stun, Kill, Revive, Radio Check. Anybody know what all of that means? I only use it for the PTT ID cause i like the sound.
Also since this topic is here, Does anyone know of a UHF mobile radio that is capable of 50 watts of output AND has MDC? The closest i have found are 45 watts.
Stun/Kill is used to 'inhibit' a radio, what effectively happens is when a radio capable of MDC receives this command, the radio appears to 'die', the radio isn't actually dead however, it is just sitting in a state of limbo quietly receiving on the frequency that stunned it waiting for a revive command. Yes MDC is capable of performing radio inhibit, typically once inhibited the only way to revive the radio is to either transmit the revive command or other methods involving the factory (or tools if your that kind of person).
Revive does the reverse of Stun/Kill which assuming the 'stunned' radio is still turned on, will let the radio resume normal operation.
Radio Check is typically sent from another radio to 'ping' (kinda like you would ping an IP on a PC).
There are a dozen other commands MDC supports as well such as paging, calling, etc etc. I only described the 3 you asked about.