BT Master Telephone Socket - Matt White Rounded Edge

The Knightsbridge CU7300 is a BT master telephone socket with a matt white rounded-edge faceplate and IDC (insulation displacement connection) terminals for incoming telephone lines. The faceplate sits 7mm proud of the wall and is moulded from thermoset resin with an anti-microbial surface treatment tested to ISO 22196:2011, making it suitable for communal areas, care homes, offices and residential installations where hygiene matters.

Designed as the first connection point between an incoming BT telephone line and the internal wiring network, the master socket provides the interface where the external service provider's line terminates and internal extensions or devices connect. The socket fits a standard 25mm minimum back box depth and uses screw terminals concealed behind removable screw cap covers, allowing clean access for line testing and fault diagnosis without dismantling the entire faceplate.

The rounded-edge profile softens the visual impact compared to traditional square-edged plates, and the matt white finish provides a neutral backdrop that works across both modern and traditional residential and commercial settings. The 86mm square footprint matches standard UK switch and socket plate dimensions, allowing coordinated installations when used alongside other Knightsbridge accessories. The IP20 rating confirms suitability for dry indoor use.

Product Specification Sheet

What is a BT master socket used for?

The master socket is the first connection point where the incoming telephone line from the service provider (BT, or other providers using BT Openreach infrastructure) terminates inside the property. All internal telephone extensions and devices connect downstream from this master socket.

What back box depth is required?

A minimum 25mm back box depth is needed for safe installation. The faceplate projects 7mm from the wall surface once fitted.

What are IDC terminals?

IDC stands for insulation displacement connection. The terminals have small blades that pierce the cable insulation when the wire is inserted, making contact with the copper conductor without needing to strip the cable first. This simplifies installation and reduces the risk of wiring errors.

Is the anti-microbial treatment permanent?

The anti-microbial properties are built into the thermoset resin material itself rather than applied as a surface coating, so they remain effective throughout the life of the product. The treatment has been independently tested to ISO 22196:2011.