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I'll admit to a large dislike for mechanical switching mechanisms, which caused me to avoid them if at all possible. Hence I can't say with certainty that 11 pulses wouldn't do something to some mechanical switch somewhere... but I've never heard of one that would not tolerate excess pulsing. (It not as if limit switches would be too complex to add!)

As for the dissolution of mechanical exchanges, by the mid-1980's the US was perhaps only about 1-3 digital!

That was an interesting transition, which as it happens was, for local telcos, pushed mostly by the cost of labor.

In the long distance business that wasn't quit the case though, because while the cost of labor for maintenance was higher in the long distance business the advent of compebreastion building separate (and all digital) long distance networks insured a very quick transition to a virtually all digital network by almost everyone. Only here in Alaska, and perhaps a few other remote areas, did analog long distance links continue to be used (until the late 1990's).

But for line switching, exactly the opposite was true! There was no compebreastion, and the only real issue was the cost of maintenance. Hence in areas with high labor costs there was a very quick transition, and in other areas it was much much slower. By 1985 Alaska was virtually 100% digital, and the US as a whole was only about 33%.

Up through about 1989 or 1990 Northern Telecom Inc (now called Nortel) marketed their DMS-100-200 switching systems as "maintenance free". That was the big selling point, and they simply would not even discuss, at a management level, tools to make maintenance easier! Tools (both hardware and software) to work on the network were no problem, but tools to work on the switch itself... were a tightly kept secret! (Which means if the telco insisted, a salesman would let them talk to an engineer about specific details; but the salesman would literally deny that such tools existed unless someone got very persistent.) It was only when NTI had cornered 40% of the market, and could see no likelihood of increasing that percentage, that they shifted from a strategy of increasing market share to one of selling more to existing customers.

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