The new system, which police say will be one of the most advanced in western Europe, comes after five years of research by the Metropolitan Police's department of technology.
Critics, however, point out that the full Metropolitan force area will not be covered by the new system for four years.
It also comes on the heels of criticism of the existing system by officers on the beat, as highlighted by Independent London last month. Police constables up to divisional superintendents have complained of poor reception and network congestion, a problem they claimed has been exacerbated by the reorganistion of the Met from eight areas to five.
The emergency button, part of the Motorola Smartzone System, will give the officers 10 seconds of instant access to the control room if they are under attack.
Nick Boothman, director of technology, said: 'The new network will reduce radio interference throughout the Met, and release a large number of radios for redeployment.
The network will benefit all radio users straight away.Reuse content