The technical field of the invention generally concerns systems for audiovisual teleservices using digital telecommunication services such as Integrated Services Digital Network ("ISDN") communications. In the preferred embodiment, an interface subsystem (100) includes an ISDN interface circuit (130)...http://www.google.de/patents/US5566301?utm_source=gb-gplus-sharePatent US5566301 - ISDN audiovisual teleservices interface subsystem
