Ambala Central Jail’s ‘call blocking’ technique to be replicated in other jails

To counter illegal mobile phone use and unauthorised communication from inside prisons, the Haryana Government has been actively deploying advanced electronic countermeasures in jails across the state.

Following the successful results of the Tower Harmonics Call Blocking System (T-HCBS), introduced as a pilot project at Ambala Central Jail, the government has decided to implement the technology in other prisons as well.

The T-HCBS is a controlled-frequency-range technological solution introduced by the Ministry of Home Affairs (MHA) to curb the unauthorised use of mobile phones inside high-security correctional facilities. It was first introduced in Haryana at Ambala Central Jail.

Unlike conventional broad-spectrum jammers, the tower-based technology blocks mobile signals precisely within jail premises without disrupting public networks in surrounding residential areas.

Haryana Cooperation, Tourism, Prisons and Elections Minister Dr Arvind Sharma said preventing the use of illegal mobile phones inside prisons was a challenging task and that curbing it remained a priority of the department.

A key feature of the T-HCBS is that it does not require the installation of conventional mobile jammers. Special towers are installed within prison premises, through which mobile phones present there can be brought under control.

“This makes it possible to prevent the use of illegal phones without completely disrupting the normal mobile network in the prison premises or areas surrounding the jail. After satisfactory results from Ambala jail, we are considering replicating the identical system in other jails after gauging technical feasibility and requirements,” he said.

Through the tower-based system, calls and internet services on illegal mobile phones present within prison premises can be controlled. This will help the prison administration curb unauthorised communication from inside prisons to the outside.

The system could prove particularly important in situations where inmates attempt to contact people outside the prison.

How the T-HCBS works

The towers are structurally optimised so that their signals remain confined to the jail premises. This prevents interference with public networks, emergency services or nearby defence installations — a critical feature for Ambala Central Jail due to its proximity to residential colonies and the Ambala Air Force Station.

The system creates a localised signal field that identifies and instantly blocks unauthorised incoming or outgoing calls, SMS and data services when they are initiated within the prison perimeter.

The system is designed to map and block communication across 2G, 3G and 4G networks, with protocols intended to address evolving and advanced mobile signals.