4.1 bonded t1's
4.2 like the other experts, i dont know what you mean by "ONE cable not 3", but i assume you mean why didn't the telco drop off ONE cable instead of the 3 individual ones? The answer is that there is no single cable solution available that gives you the same 4.5Mb data rate.
4.3 T1 and next size up is T3 which is equivelant to 23xT1, or 45Mb. You can get fractional T3 in some markets, say at 12Mb if the ISP offers it. Pricing for T3 is dramatically more, the terminating equipment much more expensive, and the delivery is typically twin coax cables with bnc connectors. The next tier up is the OCx circuit such as OC3 at about 80Mb up to OC192
4.4 dsl, cable and maybe satellite are more traditionally what are referred to as broadband, and some providers refer to their T1 service as boadband
