PMBX No. 1
BPO PMBX No. 1 and No. 1A is a lamp
calling manual switchboard with lamp supervisories. The switchboards are
bolted together to form a suite.
The number of switchboards was dependant on traffic and extensions. In addition to the switchboards a power supply, batteries, equipment rack and distribution frame were also supplied.
Introduced in 1940.
See the Ericsson section for a description.
Last revised: December 18, 2010