Crown Castle International Corp is incorporated in the State of Delaware. The Company owns, operates and leases shared wireless infrastructure, including towers and other structures, such as rooftops collectively called as towers, and to a lesser extent, distributed antenna systems, a type of small cell network, and interests in land under third party towers in various forms collectively known as wireless infrastructure. The Company's core business is providing access, including space or capacity, to wireless infrastructure via long-term contracts in the form of license, sublease and lease agreements collectively called as leases. The Company conducts its operations through tower portfolios in the United States, including Puerto Rico and Canada 'CCUSA' and Australia 'CCAL'. All of the Company's operations are located in the U.S. and Australia. Crown Castle conducts its operations mainly through subsidiaries of Crown Castle Operating Company including certain subsidiaries which operates its tower portfolios in the U.S. and a 77.6% owned subsidiary that operates its Australia tower portfolio. The core business of CCUSA is providing access, including space or capacity, to its wireless infrastructure in the U.S. The Company provides access to wireless carriers under long-term leases for their antennas which transmit a variety of signals related to wireless voice and data. The Company's sales organization markets its wireless infrastructure within the wireless communication services industry. It works with national wireless carriers, and in general, customers are comprised of providers of wireless services that operate national or regional networks. The U.S. customers include AT&T, Sprint, T-Mobile and Verizon Wireless. The competitors in Company's network services offering include site acquisition consultants, zoning consultants, real estate firms, right-of-way consulting firms, construction companies, tower owners or managers, radio frequency engineering consultants, telecommunications equipment vendors that provides turnkey site development services through multiple subcontractors, or customers' internal staff. The Company is required to comply with federal, state, and local regulations and laws in the U.S., including FCC and Federal Aviation Administration ("FAA") regulations. Both the FCC and the FAA regulate towers used for wireless communications, radio, or television broadcasting. The Company holds, through certain of its subsidiaries, certain licenses for radio transmission facilities granted by the FCC, including licenses for common carrier microwave service, commercial and private mobile radio service, specialized mobile radio and paging service.