A pager based information system is used to transmit both conventional private messages (using unique pager IDs) and two types of unconventional multi-recipient (M-R) messages (using database IDs and group IDs), all using the conventional POCSAG pager transmission format. Operation of the pager is software...http://www.google.de/patents/US4845491?utm_source=gb-gplus-sharePatent US4845491 - Pager based information system
