WANs interconnect LANs, which then provide access to computers or file servers in other locations. Because WANs connect user networks over a large geographical area, they make it possible for businesses to communicate across great distances. Using WANs allows computers, printers, and other devices on a LAN to share and be shared with distant locations. WANs provide instant communications across large geographic areas. The ability to send an instant message (IM) to someone anywhere in the world provides the same communication capabilities that used to be only possible if people were in the same physical office. Collaboration software provides access to real-time information and resources that allows meetings to be held remotely, instead of in person. Wide-area networking has also created a new class of workers called telecommuters, people who never have to leave their homes to go to work.

WANs are designed to do the following:

• Operate over a large geographically separated areas
• Allow users to have real-time communication capabilities with other users
• Provide full-time remote resources connected to local services
• Provide e-mail, World Wide Web, file transfer, and e-commerce services

Some common WAN technologies are:

• Modems
• Integrated Services Digital Network (ISDN)
• Digital Subscriber Line (DSL)
• Frame Relay
• US (T) and Europe (E) Carrier Series – T1, E1, T3, E3
• Synchronous Optical Network (SONET)

Web Links WAN Basics http://www.webwisdom.com/edu_content/ cps640fall00/lectures/ module3/WAN/ sld004.htm