File1:

An internet backbone refers to one of the principal data routes.
The data travels between large networks and core routers on the Internet.
An Internet backbone is a high-speed data transmission line.
High-speed internet service providers all around the world.

File2:

Largest companies running different parts of the Internet backbone included:
-UUNET, AT&T;,GTE Corp, and Sprint Nextel Corp.
Routers are connected w/high-speed links & support different ranges like:
-T1, T3, OC1, OC3, or OC8
The first Internet backbone was named NSFNET.
Funded by U.S. Govt.& introduced by the NSF* in 1987.
(*National Science Foundation)

File3:

T1:
a dedicated transmission connection between service provider & client;
can carry 24 voice channels for calls/digital data at a rate of 1.544Mbp/s.
Developed by AT&T; Bell Laboratories in the 1960's.
Traditional T1 lines use copper wire, most new installs use optic fiber.
In the 1970's Bell LAbs developed higher rate systems.
T2:developed capable of carrying up to 6.312Mbp/s*
*with required special low-capacitance cable with foam insulation.

No lines are longer than 80 characters, TYVM.
Other specified properties aren’t being scored automatically at this time so this is not necessarily good news…