Crown Castle International Corp is a real estate investment trust (REIT) that owns, operates and leases shared wireless infrastructure, including towers and small cell networks. The company was founded in 1994 in Houston, Texas, USA. Crown Castle operates in the United States, Puerto Rico and Australia. The company's infrastructure is used by wireless service providers to deploy small cells, distributed antenna systems (DAS), and Wi-Fi networks. Crown Castle's customers include AT&T, Verizon, T-Mobile, Sprint, and Dish Network.