Digital Subscriber Line provides internet over ordinary telephone lines. It uses frequencies above the voice band, so you can talk and browse at the same time. DSL was a bridge technology. It gave homes broadband before fiber arrived. It is still used where fiber has not reached.

DSL comes in many forms. ADSL is asymmetric: faster download than upload. SDSL is symmetric: equal speeds. VDSL is very high speed over short distances. The limiting factor is distance from the central office. The farther you are, the slower the connection. Fiber to the cabinet shortens the copper run and boosts speed.

DSL characteristics

• Uses existing phone lines
• Always on, no dialing
• Speed depends on distance
• Shared with voice service
• Being replaced by fiber

DSL was revolutionary in the 1990s. It broke the dial-up monopoly. It made the internet always available. But it has limits. Copper cannot compete with fiber. Telecom companies are phasing it out. The lines that once carried voices and data are being retired.