An unlicenced system is restricted to very low power (usually 0.5 watt) and offers absolutely no protection from interference from either legitimate and illegitimate sources. Ofcom keeps no records of the number or locations of unlicenced systems, the frequencies are effectively unregulated and are advised against in BS5839-1:2002. Common unlicenced usage includes DECT phone systems, baby monitors, wireless routers and domestic alert call systems.
A paging licence offers some protection from illegitimate interference. Take an on-site paging licence as an example, it's limited to a maximum of only 2 watt power output. Illegal broadcasts that interfere with your broadcasts and are reported to Ofcom will be investigated. However a basic paging licence offers no protection from legitimate interference. There is no overview from Ofcom on the licence application and they don't administer licences based on potential interference, they simply allocate licences. It is the responsibility of the site manager and supplier to ensure they don't interfere with any other system. As such, if you have an on-site paging licence and another licenced system interferes with yours, there is nothing you can do.
A manually coordinated category licence like the Distress Alarm Licence used by both DeafWatch (radio-based fire alarm for Deaf people) and RefugeWatch (wireless refuge communication system for managing the safe evacuation of disabled and vulnerable individuals) has direct oversight by Ofcom and ensures the elimination of legitimate interference and the investigation of illegitimate interference. Ofcom take your transmission strength and antenna location and effectively sterilise your desired area. Any future applications will take this exclusive usage area into consideration and deny a licence accordingly. Only a manually coordinated category licence can ensure broadcast security now and into the future. Additionally, licences with overview of Ofcom usually have much higher power ratings available. In the case of the distress alarm frequency, we can broadcast up to 5 watts.
