ADSL: Asymmetric DSL. Download faster than upload. Shares both voice & Internet on the same line.
SDSL: Symmetrical DSL. Download and upload speeds are same. Uses a separate dedicated Internet line and does not share voice.
T1: A leased line connection capable of carrying data at a very high speed (1.544Mbps). T1 is the fastest telephone trunk line commonly used to connect networks to the Internet.
Dialup: Dialup services include 56K, Multilink, & ISDN