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一般视像电话都是透过家用电话线传递影像及信息的,由于容量所限,影像都显得模糊不清,而声音又比影像稍慢,从而对话时就像患上了迟纯症似的。1993年IBM推出一套全新的电脑视像电话系统Screencall,视像电话在素质和功能则出现了重大的突破。该系统采用崭新的综合服务数码网络(IS-DN)传递信息。所谓ISDN,其实是数码电话线路的
In general, video telephony transmits images and messages through a home telephone line. Due to the limited capacity, the images are blurred and the sound is slightly slower than the video so that the conversation is like having a complication . In 1993, IBM introduced Screencall, a new videophone video system that made major breakthroughs in quality and functionality. The system uses a new Integrated Services Digital Network (IS-DN) to deliver information. The so-called ISDN, in fact, digital telephone lines