telecommunications services

What is Telecommunications Services?

Internetworking services provided by telcos and long-distance carriers to businesses. To link geographically separated local area networks (LANs) into a metropolitan area network (MAN) or a wide area network (WAN), businesses must lease or purchase services from their local telco and long-distance carriers because these companies own the wires that make internetworking possible.

In addition to the regular Public Switched Telephone Network (PSTN) service, most telecommunications companies offer additional services, including the following:

• Leased lines, such as T1 lines for permanent, dedicated point-to-point WAN connections
• Circuit-switched services, such as Integrated Services Digital Network (ISDN) for temporary or dial-up point-to-point WAN connections
• Packet-switched services, such as X.25 services for permanent multipoint WAN connections

Various data communication technologies are used to provide these services, including the following:

• Asynchronous Transfer Mode (ATM)
• Digital data service (DDS)
• Frame relay
• ISDN
• Switched 56
• T1 and fractional T1