The Asus DSL-N55U is a router intended for use with ADSL and ... LED’s on the front of the case usefully include one LED to show when the modem has synchronised to the DSLAM/MSAN in the telephone ...

An ISDN variant, broadband ISDN, transfers data only fiber optic telephone lines. DSL modems use digital subscriber lines (DSL) and support standard xDSL technologies to provide "always-on" Internet ...

The latter, known as Internet Protocol Broadband (IPBB), provides speeds up to 500 Mbps and uses fiber to a local multiplexer and DSL from there to the subscriber's premises (see DSLAM).