2.SDSL - Stands for Symmetric Digital Subscriber Line. Symmetric means that it supports the same data rates for upstream and downstream traffic. 3.IDSL - ISDL stands for Integrated Digital Subscriber Line. IDSL is an alternative to dial-up ISDN service, with a capacity of 144 Kbps. The difference is in downstream speeds as displayed in the table below.
Cable modems run over coaxial cable lines.
The number of users online determines access speeds from cable service. DSL is much more affordable when compared to a T-1 connection. ISDN is a technology that offers the ability for customers to dial many different locations for Internet access or other online services. The greatest advantage that DSL has over ISDN is that DSL has no usage fees. DSL is billed on a flat rate basis, similar to your local telephone service.