A Digital Subscriber Line (DSL) modem is a device used to connect a computer or router to a telephone circuit that has Digital Subscriber Line service configured. Like othermodems, it is a type of transceiver. It is also called a DSL Transceiver or ATU-R (for ADSL Transceiver Unit-Remote). The acronym NTBBA, which stands for network termination broad band adapter, is alsocommon in some countries.
Some DSL modems also manage the connection and sharing of the DSL service in a network, in this case, the unit is termed a DSL router or residential gateway. DSL routers have acomponent that performs framing, while other components perform Asynchronous Transfer Mode Segmentation and Reassembly, IEEE 802.1D bridging and/or IP routing. Typical user interfaces are Ethernet andUniversal Serial Bus (USB). Although an DSL modem working as a bridge does not need an IP address, it may have one assigned for management purposes.
Compared to voice-band modem
A DSL modemmodulates high-frequency tones for transmission to a Digital Subscriber Line Access Multiplexer (DSLAM), and receives and demodulates them from the DSLAM. It serves fundamentally the same purpose as thevoice-band modem that was a mainstay in the late 20th century, but differs from it in important ways.
DSL modems transfer data at a rate which is typically 10 to 20 times that of a voice-band modem.
Asingle telephone line can be used for simultaneous voice and data with a DSL modem whereas a voice-band modem precludes simultaneous voice traffic.
Most DSL modems are external to the computer andwired to the computer's Ethernet port, or occasionally its USB port. Internal DSL modems with PCI interface are rare but available.
Microsoft Windows and other operating systems do not recognizeexternal DSL modems connected by Ethernet, and hence have no Property Sheet or other internal method to configure them. This is because the transceiver and computer are considered separate nodes in the...