The crossbar switch

Connection of relays for crossbar exchanges at the plant of Ericsson do Brasil.

The automatic crossbar switching system was first developed within a small company called Autotelefon Betulander at about the same time as Ericsson’s 500-switch system. The crossbar switch did not need the same amount of maintenance as the motor-driven 500-system, which meant that it was very suitable for Televerket’s, the Swedish PTT, small, unmanned rural stations. 

Over time, in part through developments in the US, the crossbar switching system became suitable for very large stations, as well. By the 1940s, Ericsson began investing in the crossbar system and became its leading developer. During the 1960s, crossbar switching systems were perhaps Ericsson’s most important export product.

Author: Centre for Business History, Stockholm

© Telefonaktiebolaget LM Ericsson and Centre for Business History

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