An explanatory of how early house systems worked
The following explanatories are provided by the BTMC company of Belgium.  The parlour telephones are BTMC Model No. 3051.

Each picture shows two dry batteries of 1.5volts each.  The telephone hang on rosettes which may have a press button on them.  Depending on the manufacturer, the hook on the rosette operates a switch, when the handset is removed, or the handset has a switch which is manually operated or the handset has a switch which operates when removed from the rosette hook.  Pear shaped drop switches are also shown and these have a user operated switch on them.

We must be mindful that these were in use in the early in the early to mid 1900's, in situations where paid staff would be called upon to undertake tasks.

A simple two telephone system.
The telephone to the left can call the bell on the right and then both users can talk to each other.
The user to the right cannot call the telephone to the left.
Use - Living room to pantry.

 

A simple point to point system where both users can call the others bell and then communicate with each other.
Use - Intercommunication between two rooms.

The telephone to the left is in a central position and other telephones can call it and communicate.
The users cannot call each other individually or be called from the central telephone.
Use - allows different rooms to call the Pantry or Butlers desk.

In this system users 1 to 4 can call the central telephone (on the right).
The central users bell will ring and the indicator board will display who is calling.
The knob on the indicator board is used to restore the indicators.
Use - allows different rooms to call the Pantry or Butlers desk.  If the user is away when called
they will see on their return which room called them, as the indicator will stay operated until restored.
These systems are usually a retro-fit, where an indicator system has the remote press buttons replaced with parlour telephones.

This system allows user A to call users 1 to 3, individually, by the use of the jack panel.
If bell C is fitted then users 1 to 3 can call user A.
Users 1 to 3 cannot call each other.
Use - to allow a manager to communicate with different offices.

In this system each user can call each other and communicate.
Each user has a set of jacks and a plug.  For example, number 2 wishes to call number 3, so they move the
plug from the home jack (in this case number 2 jack) and place it in number 3 jack.  The press button is then used to ring the bell.
 Once the call is finished number 2 moves their plug back to the home position.

 

 
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Last revised: January 18, 2026
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