|  | 2.2 | WAN Devices
| 2.2.1 | Fundamental WAN devices

WANs use numerous types of devices, including the following: Routers, which offer many services, including LAN and WAN interface ports. WAN switches, which connect to WAN bandwidth for voice, data, and video communication. Modems, which interface voice-grade services. Modems include CSUs/ DSUs and TA/NT1 devices that interface ISDN services. Communication servers, which concentrate dial-in and dial-out user communication. The Figure shows the icons used for these WAN devices.
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| WAN Introduction