AT&T Archives: The Step-By-Step Switch

[Homer J Simpson]

[helius]

The step switch (or Strowger switch) was the first automatic circuit switching device. It was used for most of the 20th century, mostly in smaller population regions. Soon after, the crossbar switch came into being: the crossbar switch was favored for large metro areas due to its higher density and greater number of circuits. Each type could be identified by certain distinctive sounds they produced on the line.

http://www.wideweb.com/phonetrips/



Since the step switch was mechanical, it could only decode digits of the number synchronously as they were dialed, placing constraints on the exchanges' design. This was exploited by phone phreaks searching for special numbers.

[Red Squirrel]

Those switches were cool for their time.  I work for a telco and we have the oddball parts lying around.


 
The office where I work had a stepper switch way back in the day pretty much where I sit before they installed the DMS100.   Not sure what kind of switch exactly but it was some kind of stepper.  Tandem stepper I think.