What is a Network Service Provider (NSP)? – Definition from Techopedia

A network service provider (NSP) is a business entity that provides or sells services such as network access and bandwidth by allowing access into its backbone infrastructure or access to its network access points (NAP), which consequently also means access to the Internet. Network service providers are very similar to or can even be considered the same as Internet service providers (ISPs), but in most cases they are the ones providing backbone services to the ISPs.

Techopedia Explains Network Service Provider (NSP)

In the overall hierarchy of the worldwide network that is the Internet, network service providers are probably on top. They provide backbone access to ISPs, which in turn sell their services and provide Internet connectivity to everybody else, especially the end consumer. When a user connects to the Internet using a DSL modem or cable modem, that user connects and authenticates with the ISP, which then establishes a connection with the NSP’s backbone. The Internet itself is made up of every server and node, all connected to main backbones maintained by individual NSPs. This means that the NSPs essentially provide the infrastructure that makes up the Internet.