An Internet switch box connects between a telephone set and a public switched telephone network (PSTN) line, the latter of which is used both for PSTN telephone conversations and for connection to an Internet service provider (ISP). The switch box contains hardware and embedded software for establishing...http://www.google.com.tw/patents/US20020089975?utm_source=gb-gplus-share專利 US20020089975 - Internet switch box, system and method for internet telephony
