March 11, 2010

11:32 PM

DSL Terminology and Achronyms

DSL - Digital Subscriber Line brings high-speed Internet access over POTs or plain old telephone lines, the twisted copper pair that already brings you phone service. DSL is a distance-based technology that requires you to be within a certain distance from your CO (Central office phone company).

CO - Central Office. A telephone company facility within which all local telephone lines terminate and which contains the equipment required for switching voice communications across the telephone network. For DSL service, special equipment is set up at the CO to support DSL service for customer lines terminating at the CO.

DSLAM - Digital Subscriber Line Access Multiplexer. The device placed in a CO that accepts all the DSL lines.

ADSL - Asynchronous Digital Subscriber Line means that you will have different upstream and downstream speeds. Cherryland Online Services provides this service up to 768kbps or 1.5Mbps. This service is provided up to 10,500 feet from the CO.

Kilobits per second (Kbps) - Kilobits-per-second means thousands of bits per second. It is a common way of specifying the speed of an Internet connection; that is, the number of bits that can be transmitted over a wire in a single second. Most modem connections operate at speeds between 9.6 Kbps (9600 bits per second) and 33.6 Kbps (33,600 bits per second).

Linesharing - This is how DSL is now provided. This will put the DSL on your current phone line, without taking away your voice service. You will be able to use your phone normally, while being online at the same time. Your voice and fax will run at 4Hz and below and your DSL will share the line and use the higher frequency. This will take out Ameritech's visit to your house. However, if your phone service is turned off or does not work, for any reason you will not be able to use your DSL.

Twisted Pair - Copper wires twisted together that comprise a phone line.

Spare Pairs - These are the available phone lines on your premise. If there are no spare pairs, your order may be canceled or delayed.

Bridged Taps - The phone company will use these to make pairs available when there are not enough in the area. DSL cannot run over these. They sometimes can be removed, this will add another 2-3 weeks of installation time. A bridge tap is a technique for telephone installs, that tap you into a line that runs past your house, rather than terminating at your house. The line doesn't go to anyone else's premise, it just ends, maybe a mile up the road. This is useful should people move out, demolish a house, etc., the phone company can move the tap up or down to service whomever it wishes. Unfortunately, you have a mile of undetermined phone line running up the road and picking up interference, like a huge TV antenna. Because it isn't terminated, signals bounce up and down the line and can reinforce or cancel the signals your equipment is trying to send your ISP.

Repeaters - Put on the phone line to amplify your voice. DSL cannot run over these.

Load Coils - The phone company coils the wires for better voice quality, increases the distance from your CO. An inductor placed on the local loop by the phone company beginning at 3000 feet in 6000 feet intervals to suppress high frequency noise, unfortunately exactly the signal that DSL modems need to transmit high speed data. DSL equipment does not work through load coils.

Bridge - DSL Modem

Acronyms

NID: Network Interface Device, this is your phone box.
FOC: Firm order Commitment, Ameritech's appointment to do the cross connect
SOC: Service Order Commitment
ILEC: Incumbent Local Exchange Carrier, Ameritech, GTE, etc.
ISP: Internet Service Provider, in this case, Cherryland Online Services
EU: End User, you
CO: Central Office, the phone company's main access and switching point.