You really need to do your math. - 768x2 = 1536. DSL is full duplex.
And yes, DSL HAS been around for 20 years. The need for broadband at
inexpensive prices to the public at large has not been necessary until now,
and it's expensive to set up dslams at all these phone company CO's. Not to
mention that the phone companies, until recently, had a monopoly on the
industry, and weren't about to introduce an inexpensive broad band solution
to the public when they could make a killing off of T1 loops.
And yes, DSL HAS been around for 20 years. The need for broadband at
inexpensive prices to the public at large has not been necessary until now,
Ok.. So I mixed the physical layer and the protocol, my bad mistake.
a 1.54mbps ESF/B8ZS style 2 or 4 wire HDLC T1 has little in common
with an xDSL line at a physical level, protocol level, synchronous
bandwidth level, troubleshooting methodology, support from the LEC
or ISP level... or or... --Mike--