What Does Backbone Provider Mean?
A backbone provider is an organization or business entity that provides access to high-speed data transmission lines and other related infrastructure to other organizations that need it. This can be considered as a superset of ISPs (internet service providers). Where an ISP provides internet connectivity to end users, a backbone provider provides the ISP with high-speed connection to the internet itself.
Techopedia Explains Backbone Provider
A backbone provider is the basic foundation of the internet, providing connectivity between ISPs and between international borders. The internet backbone is defined as the principal data routes between large networks of computers and core routers on the internet. These routes are often hosted by government, large commercial organizations or academic organizations. Any organization that has control of large high-speed networks and the (usually) fiber optic trunk lines that connect them, and then subsequently lets others use the network, is considered a backbone provider.