A Network Access Device (or NAD) is an electronic circuit that automatically connects a user to a preferred network. More generally, a NAD is any device that, when connected to, provides access to a larger communication network of some sort.

Within the telecommunication industry, a NAD will be connected to a user's telephone. When the user dials a number, the NAD will 'listen' to the dialled digits and reroute the call through a network that will provide the best rates for the destination of the call. The NAD is often referred to as a dialler, predictive dialler or least cost routing

Least cost routing

In voice telecommunications, least-cost routing is the process of selecting the path of outbound communications traffic based on cost. Within a telecoms carrier, an LCR team might periodically choose between routes from several or even hundreds of carriers for destinations across the world...

 dialler.

When used in broadband a NAD (Network Access Device) is a term to describe all the subscriber equipment required to make a connection to a wide area network (WAN) from a local area network (LAN). The NAD normally includes a router, modem and a monitored power supply. Most NAD’s have the ability to report power failures and automatically reconnect themselves back to the network when disconnected.

In residential and business networks, Network Access Devices that are commonly seen include Wireless Access Point

Wireless access point

In computer networking, a wireless access point is a device that allows wireless devices to connect to a wired network using Wi-Fi, Bluetooth or related standards...

s and Ethernet switches.