Crown Castle International Corp. is an American

United States

The United States of America is a federal constitutional republic comprising fifty states and a federal district...

 corporation

Corporation

A corporation is created under the laws of a state as a separate legal entity that has privileges and liabilities that are distinct from those of its members. There are many different forms of corporations, most of which are used to conduct business. Early corporations were established by charter...

 headquartered in Houston, Texas

Houston, Texas

Houston is the fourth-largest city in the United States, and the largest city in the state of Texas. According to the 2010 U.S. Census, the city had a population of 2.1 million people within an area of . Houston is the seat of Harris County and the economic center of , which is the ...

, which provides infrastructure

Infrastructure

Infrastructure is basic physical and organizational structures needed for the operation of a society or enterprise, or the services and facilities necessary for an economy to function...

 for broadcasting

Broadcasting

Broadcasting is the distribution of audio and video content to a dispersed audience via any audio visual medium. Receiving parties may include the general public or a relatively large subset of thereof...

 and mobile telephony

Mobile phone

A mobile phone is a device which can make and receive telephone calls over a radio link whilst moving around a wide geographic area. It does so by connecting to a cellular network provided by a mobile network operator...

. It operates in the United States

United States

The United States of America is a federal constitutional republic comprising fifty states and a federal district...

, Puerto Rico

Puerto Rico

Puerto Rico , officially the Commonwealth of Puerto Rico , is an unincorporated territory of the United States, located in the northeastern Caribbean, east of the Dominican Republic and west of both the United States Virgin Islands and the British Virgin Islands.Puerto Rico comprises an...

 and Australia

Australia

Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...

. It provides mobile telephone coverage to 92% of the Australian population and 68 of the top 100 markets in the US on behalf of service providers such as 3, AT&T Wireless

AT&T Wireless

AT&T Wireless Services, Inc., founded in 1987 as McCaw Cellular Communications, Inc., and now legally known as New Cingular Wireless Services, Inc., formerly part of AT&T Corp., is a wireless telephone carrier in the United States, based in Redmond, Washington, and later traded on the New York...

, Cingular, Telefónica O2, Nextel, Orange, Sprint PCS, T-Mobile

T-Mobile

T-Mobile International AG is a German-based holding company for Deutsche Telekom AG's various mobile communications subsidiaries outside Germany. Based in Bonn, Germany, its subsidiaries operate GSM and UMTS-based cellular networks in Europe, the United States, Puerto Rico and the US Virgin Islands...

, Verizon, and Vodafone

Vodafone

Vodafone Group Plc is a global telecommunications company headquartered in London, United Kingdom. It is the world's largest mobile telecommunications company measured by revenues and the world's second-largest measured by subscribers , with around 341 million proportionate subscribers as of...

.

On August 31, 2004 Crown Castle completed the sale of its UK subsidiary, Crown Castle UK, to National Grid Transco plc for $2.035 billion in cash. National Grid Transco plc was renamed as National Grid plc

National Grid plc

National Grid plc is a multinational electricity and gas utility company headquartered in London, United Kingdom. Its principal activities are in the United Kingdom and northeastern United States and it is one of the largest investor-owned energy companies in the world.National Grid is listed on...

 in July 2005, while Crown Castle UK was renamed National Grid Wireless in October 2005.

On January 12, 2007, Crown Castle completed the acquisition of Global Signal Inc., a rival U.S. tower operator which was based in Sarasota, FL.