Femtocells are low-power cellular base stations used in homes and small offices to improve indoor mobile coverage. They connect to the operator’s core network over broadband and broadcast a local cellular signal, typically covering 10 to 50 metres.

They operate within standard mobile infrastructure, using licensed spectrum such as:

• 3G UMTS bands (Band 1 2100 MHz in the UK)

• Some later units support LTE bands depending on deployment

Unlike signal boosters, femtocells do not amplify an existing signal. They create a new one, and devices will automatically connect if it presents the strongest signal.

Image 1: Legacy femtocell device originally deployed by mobile networks, now circulating in secondary markets despite being phased out.

The issue

Femtocells extend the cellular network directly into private environments.

• Traffic is routed through broadband

• Devices connect based on signal strength, not trust

• The cellular layer becomes localised and harder to monitor

This creates a gap between:

•…