Security systems

A security system includes a remote operations centre (4) which has a point of presence (53) on a connectionless network (internet) (52). A home control unit (44) which holds a list of release codes for associated security aware apparatuses (not shown) communicates with the remote control centre which creates release codes in dependence upon the location (or identity) of the home control unit and the requesting apparatus. The home control unit may include GPS detection circuitry to allow location data to be forwarded together with requests so that unauthorised relocation of a home control centre results in the return of invalid or no data. Requests and responses between the centre and the home control units may alternatively be made using electronic mail messaging between respective electronic mailboxes. In a further feature, security aware apparatus may communicate directly with the remote control centre through connectionless network messaging.