The No. 1ESS was basically a No 5XBAR with stored program control (SPC). The real motivator was to cut labor cost and secondarily to be able to market special calling features.
Not knocking that nice forward step in switching, but it was good for Ma Bell first, and the customer could (would) ride along for whatever benefits it gave to the subscribers.
[TELECOM Digest Editor's Note: I have said more or less the same thing for several years. Please recall that through the 1960's, fraud against the telephone company had reached scandalous levels. Everyone, or nearly everyone 'who mattered' knew how 'the system' worked. No one paid for anything from telco they could avoid. For example, consider the old style 'calling cards' with the numbers and 'key letter' combination. Calling cards _used to_ consist of the RAO (Regional Accounting Office) code, ten digits (a/c plus phone number) and a 'key letter' (such as 'A' though 'J') . As their little secret, telco took one of the ten digits [normally the fourth, fifth or sixth digit] of the phone number, and tied it into the 'key letter'. For example, if the fifth digit in your phone number was a '7' then the key letter for that year was 'B'. Bell would announce in internal memos each year what (positioned) digit would be used, and what letter would be associated. No one was supposed to know how it worked, except for telephone operators, so that if you said to the operator that you wanted to make a calling card call she could at least tell if you got the logistics correct (by the key letter and number thing) even if you were full of malarkey about the number to be charged, which she could _not_ tell if you were using a pay station. Illinois Bell wrote off _millions of dollars_ in calling card fraud each year, as did New York Telephone.Things had gotten to be so bad that not only did people rip off phone calls like crazy (most phreaks never paid for phone calls) but far too many people otherwise were 'too smart for their own good' in Bell System's opinion on things such as how calls were traced as needed. A phreak once said to me, "pay no attention to all that stuff in the movies where someone calls the operator and says 'trace that call I just recieved'; I can tell you that _if_ an _attempt_ is made to trace the call, they will send some guy back to the frames, he is going to look and look and look and look some more then he will discover the origin of the call is some other central office so he has to call over there, and someone there has to go in the frames and look and look and look and look some more. And just about the time he thinks he has the call traced, he hears a sickening crash as the tandem (call connection circuitry) collapses because the call was disconnected, and it was a wasted effort. So if I am 'on a call' and some old bitch tells me she is going to 'have the call traced' and get me in trouble I just her 'go ahead and do that' ... I figure I can chat with her for another
20-30 minutes at least before it gets to the point that it is going to matter."In Chicago, there was an 'elite society' of phreaks who always had a meeting once a year in January: after first making solemn oaths to _not_ abuse each other's personal calling cards, everyone laid their calling card out on a table for everyone else to see. The idea was to by process of elimination detirmine the formula for the key letters and which positioned digit was chosen for that year. The more people present, the wider variety of examples to use in seeing how it worked for that year. Once they were reasonably certain how things would work, they put in a couple of 'test calls', to verify their hypothesis (this year it is the digit in the nth position, and the associated letters are [etc]).
Bell got hit so bad for a few years, they finally decided they had to rebuild the entire phone system from the ground up, and the answer to that was ESS. So as you stated, Bell did not develop ESS in order to make a few dollars selling 'custom calling features' to users; ESS was developed so the telephone company could regain control of a network which was rapidly getting out of control. When Bell was able to give users a free (or nearly free) ride on the new technology, they did so. They didn't develop 'caller ID' or 'call waiting' or 'three way calling' for _your_ benefit; everything Bell did was for its own benefit first and foremost. PAT]