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DSL Service - Frequently Asked Questions

• What speed of DSL can I get?
• What is a Central Office?
• What is a Remote Terminal?
• If DSL has download speed of "Up to 1.5Mbps", what will my actual speed be?

What speed of DSL can I get?

The speed of a DSL line is directly related to the length of the telephone wire between your house and the telephone company's Central Office or Remote Terminal. This distance is referred to as the "Loop Length"

This chart shows you the maximin loop length for different types of DSL

When you place an order for DSL service, we check your phone number in an AT&T database that gives an estimated loop length. If the distance is within 6,500 ft of a CO, then you can order any speed service you want. If you are between 6,500 and 9,500 ft, then you will be able to qualify only for Advanced or Primary Plus.

Keep in mind that these numbers are just estimates, If may be that the actual loop length is longer than the estimate, so if you live at the outside edge of the loop length, you may not be able to get the service that was ordered.

What is a Central Office?

When the telephone network was first installed many years ago, the telephone company placed a grid over the city map, and decided that all buildings within a particular cell would have their wires run back to a central location, and on that central location they built a building to house all the wire terminations. These Central Offices were typically dull looking buildings with no windows in them. The Berkeley Main CO is on Bancroft St., just east of Shattuck Ave.

What is a Remote Terminal?

When people started building houses further away from the Central Office, the telephone company started to build small "remote terminals" that would serve these people. A remote terminal is connected to the CO with high speed fiber-optic cables, which are converted to copper wires for connectivity to individual house in the area. These can be equipped with a DSLAM (Digital Services Line Access Multiplexer) to allow customers being served by a remote terminal to get DSL service.

If DSL has download speed of "Up to 1.5Mbps", what will my actual speed be?

Your speed, both upload and download, will depend entirely on your loop length. If you lived across the street from the CO, then you would likely get very close to the maximum speed (1.5mbps download). The further away you are, the less that speed will be. Customers at the farthest reaches of DSL (at 15,000 ft.) may only get 300kbps.