radiocommunications-based service involving non-speech, one-way, personal selective calling with a tone, vibration or visual alert. The system may either simply inform the user that somebody is trying to contact him or her or may also carry a numeric or alphanumeric message., service which provides the subscriber with the facility, by means of portable equipment used in a given area, to receive an alert by radio initiated by any telephone in a public network; the alert can be accompanied by a spoken message or visual coded display either entered by the caller or generated within the network, a one-way radio communication service which by means of a network of transmitters broadcasts the identity code or call sign of a small pocket receiver, or pager. The pager monitors the broadcast channel continuously but responds by ‘bleeping’ or vibrating only when it recognises its own call sign., a service enabling customers equipped with pocket-sized receivers to be given an audible indication that they are required to take some prearranged action, usually that of calling a particular phone number