The Difference Between ADSL & DSL

Digital Subscriber Line (DSL) is a type of broadband or high-speed Internet access. The two types of DSL are Asymmetrical Digital Subscriber Line (ADSL) and Symmetrical Digital Subscriber Line (SDSL).

Background

DSL sends data over already installed copper telephone lines to homes and businesses. The speed of DSL ranges from several hundred Kbps to millions of bits per second.

ADSL

ADSL data travels faster from the server to the customer than from the customer to the server. That is, ADSL has higher download speeds than upload speeds. Residential customers typically use ADSL, which doesn't interfere with telephone calls.

SDSL

With SDSL, the speed of data transfer is the same in both directions. Businesses often use SDSL for services such as video conferencing. The faster forms of SDSL include High-data-rate Digital Subscriber Line (HDSL) and Very High-data-rate Digital Subscriber Line (VDSL).

Availability

ADSL is more widely available than SDSL.

Considerations

According to the Indiana Office of Utility Consumer Counselor, ADSL must be within 18,000 feet of the telephone company's central office, while SDSL must be within 12,000 feet, although new technologies can extend DSL capabilities up to 25,000 feet.

References

• FCC Consumer Facts: Getting Broadband
• Broadband Primer