A network service provider (NSP) is a business or organization that sells bandwidth or network access by providing direct backbone access to the Internet and usually access to its network access points (NAPs). For such a reason, network service providers are sometimes referred to as backbone providers or internet providers.

Network service providers may consist of telecommunications companies, data carriers, wireless communications providers, Internet service providers, and cable television operators offering high-speed Internet access.

Gartner listed the world's top NSPs in 2004 as:-

• AT&T based in USA
• MCI based in USA
• BT based in UK
• NTT Communications Corp based in Japan
• SingTel in Singapore

Within the United States, major network service providers include MCI, Sprint, Level 3 Communications, and AT&T.

A few information technology companies are also emerging into the NSP market, notably IBM, EDS, CSC, Vanco and Atos Origin. This is due to the convergence of information technology and communications technology into one Information and Communications Technology (ICT).