Broadband Modems in High-Speed Internet Access and Use

Modem and Cable on a Desk
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A broadband modem is a type of computer modem used with high-speed internet services. The three common types of broadband modems are cable, DSL (digital subscriber line), and wireless. (Traditional computer modems, in contrast, support low-speed dial-up internet, which is considered nearly obsolete in areas where broadband service is available.) 

The definition of broadband speed varies by country, and some DSL and wireless services using older technology can fall below the official limits. Nevertheless, they are all considered broadband modems.

Wired Broadband Modems

cable modem connects a home computer (or network of home computers) to residential cable lines for the purpose of internet connectivity. Standard cable modems support a version of the DOCSIS (Data Over Cable Service Interface Specification). In contrast, a DSL modem connects to residential public telephone service for internet connectivity.

Cisco DPC3008 Cable Modem
A Cisco DPC3008 Cable Modem. Cisco Systems, Inc.

Both cable and DSL modems enable the sending of digital data over physical lines designed for analog communications (voice or television signals). Fiber internet (for example, that used by Verizon FIOS) does not require the use of a modem, because fiber optic cables support all-digital communications.

Wireless Broadband Modems

Wireless modem devices that connect to 3G or 4G cellular internet services are commonly called mobile hotspots (not to be confused with Wi-Fi hotspots). Technically speaking, you can use a smartphone as a wireless modem when you connect it to another local device in tethering mode.

Fixed wireless broadband services sometimes require a modem for connecting the home network to the provider's local radio equipment; this depends on the technology involved.

Using Broadband Modems

Like a television set-top box, both cable and DSL modems typically are supplied by the internet service provider, so it's not a piece of equipment you have to shop for on your own (although most providers allow you to buy your own if you choose). Broadband modems are sometimes also manufactured together with broadband routers and sold as single units commonly called home gateways or residential gateways. 

When installing separately, a broadband modem connects to the internet on one end and to the internal home network on the other. The modem-to-router link can use an Ethernet or USB cable, depending on which options each device supports. The modem-to-internet connection uses a telephone line (DSL) or coaxial cable line (for cable modems).

Connectivity Issues

When Microsoft Windows detects a problem with your broadband connection, it displays a message something like this: "Your broadband connection is experiencing connectivity problems." Although the message refers specifically to the modem, this error can indicate other problems, too:

  • Setup issues or malfunctions with the broadband router
  • Connection issues between the Windows computer and the router
  • Malfunctions with the modem itself

Unlike routers, modems have few settings and troubleshooting options. Typically, administrators must power a modem off and then back on to reset it. For best results, power both the broadband modem and router off and on together.