The MIT Dormitory Telephone System
MIT Dormphone - II

EQUIPMENT - Switches

EQUIPMENT - SwitchesDormphone was entirely a Strowger or Step-by-Step system. The calling party was connected to the switching equipment by either lineswitches or linefinders. Both are shown in the Home Page picture, which shows Everett Butcher working on the lineswitches. All dialled digits except the last two were recorded on selector switches, each of which recorded one digit and then searched for a subsequent switch to accept the next digit(s). The final two digits were recorded on connector switches, the most impressive of which was the "trunk and level hunting" connector. While the general structure of one of these (shown at left) was the same as the other switches, it had a LOT more relays. If someone called a line that was busy, but the called location had more one line, the switch would automatically advance to the next line. We once jiggered one of these switches to hunt the maximum number of lines (100); it took 11 seconds. The dormitory desks and the student radio station (the original WTBS) were the only places that had multiple lines, but I think the maximum "hunt group" for these was three lines.

Next: EQUIPMENT - Test Desk and The End

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