How ISDN at basic rate can accross ordinary telephone line transmit datas at rate 2*64+16 kbs = 144 kbs while modem can only at max 56 kbs. I understand one B channel can support 64 kbs because digitalisation, D channel can support 16 kbs because it is transmited outband with different fruqency range than B channel. What is with rest 64 kbs - second B channel ? I assume that ISDN use second physical (from twisted pair) wire for one B channel which is used for electricity at ordinary phone or modem traffic but I am not sure.
Second question:
What additional equipment local telephone exchange (it's already digital) must have to support ISDN ? I assume some equipment for SS7 for D channel, and some store and forward capacity. Does anyone know what and names of that equipment ?
Second question:
What additional equipment local telephone exchange (it's already digital) must have to support ISDN ? I assume some equipment for SS7 for D channel, and some store and forward capacity. Does anyone know what and names of that equipment ?