ISDN (Integrated Services Digital Network). The phone company could much more efficiently transport digital traffic if it used an
end-to-end all-digital technique. Even though the long distance circuits are digital, the local loops are not. If
the local loops were also digital, the data would arrive at the phone exchange in a much more compact form, which
would be cheaper to transport over the long distance lines. ISDN is way to convert your local phone loop to all
digital. You rent a special modem from the phone company that gives you 64,000
bits or 128,000 per second. Because of the high capital costs, and because such
technology is obsolete before the ink on the plans is dry, ISDN implementation has been progressing very slowly.