112 is the European telephone number for the emergency services. The European Union has been growing at such a rapid rate and travel between these now borderless countries has become so simple it was decided some years ago to use one Europe wide number instead of a whole load of different national numbers. Many countries changed their old national numbers for 112 but (anti-Europe) Britain didnt want to fall in line and has kept 999 as its national number.
Britain does however take part in the scheme but they dont advertise the fact to the British public. It is mainly used by holidaying Europeans. Which ever number you use you will make contact with the emergency services.