HOW DOES AN A&B COINBOX OPERATE

A&B coin boxes came in two types: pre-payment and post payment.  Pre-payment is used on automatic exchanges, where the money is inserted before you can dial and post payment is used where manual exchanges are used.

On post payment types there is no dial on the telephone and the operator answers when the handset is lifted.  The operator will advise when and how much money should be inserted.  See the section below on operator assistance.

This section is about pre-payment A&B working on Automatic exchanges and assumes that the coin box uses a Mechanism No. 14, which is pre-decimal, uses four pennies for a fixed local call charge and has provision for 1d (penny), 6d (sixpence) and 1s (Shilling).

The dial on these systems has an extra contact that allows the digit 9 and 0 to be dialed with no money requirement.  This means that 0 (operator) and 999 (emergency) calls can be made.

To make a local call the handset is lifted and 4 pennies are inserted.  These pennies go into a basket and rest on a counter balanced swinging arm.  The arm will drop when four pennies are inserted and a contact operates, which switches on the transmitter in the handset.

In the line is busy then the "B" button on the side of the mechanism is pressed and the 4 pennies are returned to the caller via the reject shute.

If the called number answers then the caller presses the "A" button on the front of the coin box, the basket swings away from the swinging arm and the pennies fall into the cash box.  The caller can then speak for as long as they wish as there is no call timer on local calls.

If the call is long distance or operator assistance is required then the digit 0 is dialled and the caller is connected to the operator without any coins being inserted at this point.  The operator is then in control of connecting the call and will advise of what monies to insert as the call is connected.  The operator knows what coins are inserted because the 1d coin hits a wire gong, the sixpence hits a bell gong once and the shilling hits the bell gong twice.  The bell gong has a small  carbon transmitter connected to it and this is how the operator hears the gong.

If the call is successfully connected the caller is instructed to press button "A" and if busy instructed to press button "B" to get the money returned.

As the operator was in control of the call, they could request further coins to be inserted during the call or disconnect the caller if they refused to pay.