UUNET founded in 1987, was one of the largest Internet service providers and one of the early Tier 1 networks. It was based in Northern Virginia and was the first commercial Internet service provider. Today, UUNET is an internal brand of Verizon Business (formerly MCI).
Mergers and acquisitions
In 1996, UUNET was acquired by MFS.
In 1996, UUNET was acquired by WorldCom as part of WorldCom’s purchase of MFS Communications Company.
In 2001, UUNET was fully integrated with WorldCom and the name was dropped from all official documents.
In 2002, the owner of UUNET at that time (WorldCom) filed for what was then the largest Chapter 11 bankruptcy protection in history.
As of 2005, its Internet service and infrastructure, assigned AS701 maintained the highest outdegree of any ISP.
Verizon — In 2006, WorldCom was purchased by Verizon Communications and now operates under the Verizon Business name. Source: https://en.wikipedia.org/wiki/UUNET