Interesting stuff. I reckon this is the system that was announced to the Press just a day or so before MGR went into Administration.
Apologies for not following closely, but is the silver box specific to 75/ZT or was it available as part of another kit? If the latter, then all that is needed is some wiring which could be copied from the pics. Assuming it is that simple. But would you have to use a Nokia phone from c.2005
or would a modern phone work too?
EDIT: PDF date is 2003, so must be an earlier system, or seriously delayed? Say ;available now' though.