This is wonderful! I had no idea the museum, nor the Telecommunications History Group, existed. Having worked in Bell Canada for many years I had the pleasure of working on many kinds of switches including DMS-10s and also DMS-100, DMS-200/250, Step-by-step, crossbar, SP1 and PBXs including 701, SL1 etc (not to mention 1A and 6A key systems, Dataroute, T-carrier and many other analog and digital systems). Interesting side note. If, as a telecom technician, you were weened on mechanical switch systems like step-by-step, you really understood call processing at a level that carried well through to hybrid and all digital systems whereas techs who entered the scene at the digital stage didn't have the same (or so it seemed) level of understanding which made a big difference in troubleshooting CO problems.