Residential gateway

The WAN is a larger computer network, generally operated by an Internet service provider.

[3] It merely allows ATM or PPP or PPPoE traffic to be transmitted across telephone lines, cable wires, optical fibers, wireless radio frequencies, or other physical layers.

[4] On the receiving end is another modem that re-converts the transmission format back into digital data packets.

[5] This allows network bridging using telephone, cable, optical, and radio connection methods.

The modem also provides handshake protocols, so that the devices on each end of the connection are able to recognize each other.

A typical residential gateway. A single internet connection is shared by multiple devices connected through a LAN.
An internet box integrating a SIM Card