This wall type replaces the OA 500.

These are wall mounted switchboards with press buttons (sometimes called pyramid switchboards) which can be combined with a normal telephone sets.

For double lines Local battery system.

The connections are made by means of keys.

The OA 510/4 is shown pictured.

Frame of veneered oak.
Switch buttons.
Push buttons in the bottom row - one for each line - for release any of the lines on the telephone combined with the wall switch.
Indicators - one for each line.
Bell.
Switch for switching on the Bell or an additional bell on night service.

Since this switch has no generator or microphone, it must be associated with an appropriate telephone set.

In case of a signal coming from outside, the corresponding indicator and the switchboard bell operate. The operator then lifts the flap, on the indicator, whereupon the bell stops ringing.  The corresponding push button is then pressed on the bottom row to answer the call on the telephone set.  The operator then pulls out the button that was just pressed and presses the button in the bottom row which corresponds to the desired line, and gives a signal by means of the telephones generator. Then the last pressed one is pulled out again button, and the caller is connected to the desired line by pressing the corresponding button in the upper row.

When the call has ended and the the telephones go on hook the indicator drops and the bell rings, after which the operator pulls out the activated button and raises the flap.

On special order, at an increased price, these switchboards can be made in walnut, mahogany or teak.

Taken from the L. M. Ericsson Catalogue No. 122 (1930)
 

Last revised: March 31, 2024