[1] Prior to this, contact by emergency service personnel with their control rooms was made by telephone.
[2] Radio schemes run by DTELS consisted of ten wireless depots throughout England, Scotland and Wales, supplemented further by around sixty outstations.
An oddity of the system was that call signs were often spoken as letters rather than phonetically: "MP" would be said as "Em-Pee" rather than "Mike Papa".
[5][2] In 1991 the Directorate of Telecommunications officially changed its name to DTELS and four years later became a private sector company following a trade sale to National Transcommunications Limited (NTL).
[6] Airwave now has a nationwide network of more than 3,000 sites and provides secure voice and data communications to over 300 public safety organisations.