The invention concerns placing an exploratory telephone call to a party, using a first telephone channel, in order to inquire whether the party wishes to hold a video conference. If the party does, the caller then actuates the invention, which establishes an initial video conference on a second...http://www.google.com/patents/US5717857?utm_source=gb-gplus-sharePatent US5717857 - System for switching data connection to use first channel and second channel without substantial interruption of transfer of audio signals and image data between computers 
