Digital subscriber line access multiplexer

A Digital Subscriber Line Access Multiplexer (DSLAM, often pronounced dee-slam) allows telephone lines to make faster connections to the Internet. It is a network device, located in the telephony exchanges of the service providers, that connects multiple customer Digital Subscriber Lines (DSLs) to a high-speed Internet backbone line using multiplexing techniques. By placing remote DSLAMs at locations remote to the telephone company central office (CO), telephone companies provide DSL service to locations previously beyond effective range.

* DSL modems vary in data speed from hundreds of kilobits per second to many megabits, while voiceband modems are nominally 56K modems and actually limited to approximately 50 kb/s.

* DSL modems exchange data with only the DSLAM to which they are wired, which in turn connects them to the Internet, while most voiceband modems can dial directly anywhere in the world.

* DSL modems are intended for particular protocols and sometimes won't work on another line even from the same company, while most voiceband modems use international standards and can "fall back" to find a standard that will work.[citation needed]

Most of these differences are of little interest to consumers, except the greater speed of DSL and the ability to use the telephone even when the computer is online.

Because a single phone line commonly carries DSL and voice, DSL filters are used to separate the two uses.