Halo’s Radio Frequency systems provide RF signals which block all mobile phone channels in the coverage area, with the exception of the authorised devices which are free to access their cellular network carrier. There is minimal signal leakage from the facility, allowing the continued use of public mobile phone signals outside the prison perimeter. Due to the modular design of Halo™, it can be upgraded and extended at any time, to include other areas of the facility, or adjoining buildings that require mobile phone control.