T1 can carry the equivalent of 24 voice or data channels, giving a max throughput of 1.544Mbps.
The cost varies from region to region. The longer the distance between the provider and the subscriber the higher the monthly charge. Charges for local T1 are based in mileage, where as long distance varies from city to city.
Fractional T1, allow organizations to use some of the channels on a T1 line and be charged according the number of chanels they use. Fractional T1 bandwidth can be leased in multiples of 64Kbps.
DSL is not available in all areas and may be subject to distances limitations. There are different types of DSL like:
ADSL, G lite, HDSL, SDSL, VDSL. Each of them has different characteristics and throughput. Also their prises varies.
A home user most likely uses Asymmetrical DSL (ADSL) which provides more throughput downstream than upstream and its higher speed is limited to a distance of 12,000ft. The only type of DSL that provides the same amount of bandwidth downstream and upstream, i believe is SDSL.
Also even that the ISP said that DSL speed is 1.544Mbps the FCC regulates how much throughput they can actually provide, not to said that ISP also regulates the throughput thus you will never actually be able to use the full 1.544Mbps. Also the throughput varies depending how many people shares the same line making it unable to provide a constant bandwidth.
While in the other side T1 provides businesses and organizations with constant bandwidth and better speeds for those who need to upload information as much as download, while some types of DSL provide less speed for uploading than downloading.
There is more to it like the type of signal transmission, type of multiplexing, type of modulation, signal level, cabling and others that will take too much space to write it here.
Hopefully this give you a little introduction to the topic!
