A wideband communication facility is established via a switched network between calling and called terminals. The wideband facility comprises a number of segments, each segment including a plurality of narrowband time division multiplex channels having a total bandwidth at least equal to the bandwidth...http://www.google.de/patents/US4704716?utm_source=gb-gplus-sharePatent US4704716 - Method and apparatus for establishing a wideband communication facility through a communication network having narrow bandwidth channels
