Alltel

ALLTEL Corporation is an American telecommunications company with headquarters in Little Rock, Arkansas. Alltel provides wireless services to residential and business customers in all 50 states through roaming agreements. With its own network in 34 of those states Alltel's own wireless coverage area comprises the largest network by square miles covered in the United States.

Alltel was bought by TPG and Goldman Sachs in 2007 for $27.5 billion

Sources:
http://en.wikipedia.org/wiki/Alltel