L. M. ERICSSON
SWITCHBOARD OA 150

Type OA 150
Cordless Switch, Wall Pattern
Earth or Metallic Circuit
Local Battery System

To be used in conjunction with any ordinary telephone instrument.

The connections are made by means of key switches.

The switch is intended to be combined with a normal telephone set. Incoming calls can be indicated by the flap falling and a bell signal.  The bell is powered by means of batteries.

The keys are normally be in the middle position. At signal coming from outside
falls the corresponding indicator flap and the possibly the bell, operate. The flap is then restored and the line key switched downwards. The operators handset is then lifted. The caller advises of whom they wish to speak to and the key is then placed in the down position.  The operator then calls calls the required telephone by means of the generator. On transfer, the requested line's key is placed in the upper position, whereby the two lines are connected together.

When the call is finished and the indicator flaps fall. The keys and indicator flaps are then restored to their normal position.

At the same time as two lines talk to each other, the third line can stand still in call connection with the exchange.

The switchboard can communicate with any of the lines  by operating the corresponding switch which is placed in the lower position, after which dialing, speech can take place in the usual way.

These switchboards are actually intended for double lines but can also be used for single lines. In this case, only 3 of the line terminals will be occupied by line-wires, the other 3 are connected to the earth terminal which when the switch was used for double lines, not used.

On special order, at an increased price, these gears are made in walnut, mahogany or teak.

FRAMEWORK
Polished walnut. The front face is covered with fibre.

CAPACITY
3 Earth or Metallic Circuit Lines.

EQUIPMENT
3 Switching Keys.
3 Calling and Clearing Indicators.
1 Night Bell Switch.

DIMENSIONS
Height 6.3 ins
Width 5.9 ins
Depth 5.9 ins

Weight, 3.74 Lbs.

Superseded by the AO 1000.

Taken from the Ericsson Telephone Catalogues 1914 and 1930

Last revised: March 31, 2024