[GreenKeys] Types Of Central Office Switches

[Steve Hilsz]

Mention was made of types of Central Office switches used by various Bell 
and Independent Operating Companies.

The Bell System generally employed a type of machine switching called 
"Panel" in their larger metropolitan areas. This was mammoth equipment, 
suitable only for large exchanges.

Smaller Bell exchanges used a derivative of the Automatic Electric Strowger 
system called "Step by Step." The switches stepped up and in a semi-circle. 
Usually, these systems were upgraded to a relay-type system called 
"Crossbar,"

General Telephone System used Strowger step switch offices. Continental and 
other Independents usually opted for Stromberg-Carlson "XY" offices, in 
which the switches were flat and stepped sideways and forward in an "X" and 
"Y" plane.

Some Independents used all-relay switches, usually manufactured by North 
Electric Company.

Steve Hilsz