The T2000s expose options connections internally which made them popular for interfacing with data systems like those previously found in Taxis. It's not always possible to tell externally which board has been fitted, and various boards exist - some of which are undocumented.

These were found in a pair of radios purchased from a radio rally. There was no indication on the outside of the radio these boards had been fitted. The boards appear to operate as data modems, possibly 9600 baud GMSK. Note this isn't compatible with G3RUH's 9600 baud specification.

It's a busy board and no schematic or documentation has been found at present, and the presence of the TCXO circuitry usually found on a separate module makes it difficult to just remove the options board without somehow providing the missing TCXO function.

Almost all the pins on the 15 pin DE-15 connector are connected to the rest of the circuit with small SMD resistors, so some scope exists to remove them and insert “bodge wires” to bridge out the rest of the circuit but this is so far untested.