A network service provider (NSP) is a business or organization that sells bandwidth

Bandwidth (computing)

In computer networking and computer science, bandwidth, network bandwidth, data bandwidth, or digital bandwidth is a measure of available or consumed data communication resources expressed in bits/second or multiples of it .Note that in textbooks on wireless communications, modem data transmission,...

 or network access by providing direct backbone

Internet backbone

The Internet backbone refers to the principal data routes between large, strategically interconnected networks and core routers in the Internet...

 access to the Internet

Internet

The Internet is a global system of interconnected computer networks that use the standard Internet protocol suite to serve billions of users worldwide...

 and usually access to its network access point

Network access point

A Network Access Point was a public network exchange facility where Internet Service Providers connected with one another in peering arrangements. The NAPs were a key component in the transition from the NSFNET era when many networks were government sponsored and commercial traffic was prohibited...

s (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 provider

Internet service provider

An Internet service provider is a company that provides access to the Internet. Access ISPs directly connect customers to the Internet using copper wires, wireless or fiber-optic connections. Hosting ISPs lease server space for smaller businesses and host other people servers...

s, and cable television

Cable television

Cable television is a system of providing television programs to consumers via radio frequency signals transmitted to televisions through coaxial cables or digital light pulses through fixed optical fibers located on the subscriber's property, much like the over-the-air method used in traditional...

 operators offering high-speed Internet access.

Gartner

Gartner

Gartner, Inc. is an information technology research and advisory firm headquartered in Stamford, Connecticut, United States. It was known as GartnerGroup until 2001....

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

• AT&T
  AT&T
  AT&T Inc. is an American multinational telecommunications corporation headquartered in Whitacre Tower, Dallas, Texas, United States. It is the largest provider of mobile telephony and fixed telephony in the United States, and is also a provider of broadband and subscription television services...
  
  : based in the USA
• Verizon: based in the USA
• BT: based in the UK
• NTT Communications Corp
  NTT Communications Corp
  or NTT Com, is a subsidiary of Nippon Telegraph and Telephone Corporation - one of the world's largest telecommunications companies. NTT Com provides network management, security and solution services to consumers, corporations and governments....
  
  : based in Japan
• SingTel
  Singapore Telecommunications
  Singapore Telecommunications Limited , commonly abbreviated as SingTel, is a Singaporean telecommunications company, with a combined mobile subscriber base of 416 million customers from its own operations and regional associates in 25 countries at end of June 2011 increased by 19 percent from a...
  
  : based in Singapore

Within the United States

United States

The United States of America is a federal constitutional republic comprising fifty states and a federal district...

, major network service providers include AT&T

AT&T

AT&T Inc. is an American multinational telecommunications corporation headquartered in Whitacre Tower, Dallas, Texas, United States. It is the largest provider of mobile telephony and fixed telephony in the United States, and is also a provider of broadband and subscription television services...

, Verizon, Sprint, and Level 3 Communications

Level 3 Communications

Level 3 Communications is a telecommunications and Internet service provider headquartered in Broomfield, Colorado.It operates a Tier 1 network. The company provides core transport, IP, voice, video and content delivery for most of the medium to large Internet carriers in North America and Europe...

.

A few information technology companies are also emerging into the NSP market, notably IBM

IBM

International Business Machines Corporation or IBM is an American multinational technology and consulting corporation headquartered in Armonk, New York, United States. IBM manufactures and sells computer hardware and software, and it offers infrastructure, hosting and consulting services in areas...

, EDS

Electronic Data Systems

HP Enterprise Services is the global business and technology services division of Hewlett Packard's HP Enterprise Business strategic business unit. It was formed by the combination of HP's legacy services consulting and outsourcing business and the integration of acquired Electronic Data Systems,...

, CSC

Computer Sciences Corporation

Computer Sciences Corporation is an American information technology and business services company headquartered in Falls Church, Virginia, USA...

, Vanco

Vanco

Vanco Group Limited is a British telecommunications company. It is a Virtual Network Operator, owning no network infrastructure itself, but providing management services and reselling network from other telecommunications suppliers...

 and Atos Origin

Atos Origin

Atos S.A. is an international information technology corporation which operates in 42 countries worldwide, with over 78,500 employees...

. This is due to the convergence of information technology and communications technology into one Information and Communications Technology (ICT).