ADSL modem or DSL modem is a device used to connect a single computer or router to a DSL phone line, in order to use an ADSL service. Like other modems it is a type of transceiver. It is also called a DSL Transceiver or ATU-R. The acronym NTBBA (network termination broad band adapter, network termination broad band access) is also common in some countries.
Some ADSL modems also manage the connection and sharing of the ADSL service with a group of machines: in this case, the unit is termed a DSL router or residential gateway. DSL Routers have a functional block which performs framing, while other functional blocks perform Asynchronous Transfer Mode Segmentation and Reassembly, IEEE 802.1D bridging and/or IP routing. Typical user interfaces are Ethernet and USB. Although an ADSL modem working as a bridge doesn't need an IP address, it may have one assigned for management purposes.