SBA Communications owns and leases roughly almost 30,000 cell towers throughout North America and South America. It leases space on its towers to wireless service providers, who install equipment on the towers to support their wireless networks. The company has a very concentrated customer base, with most revenue in each market being generated by just the top few mobile carriers. The company owns more than 16,000 towers in the U.S., which accounted for three fourths of the company's total revenue in 2018. Internationally, SBA's greatest presence is in Brazil, where it operates more than 8,000 towers. SBA operates as a real estate investment trust, or REIT, but does not expect to be required to pay a dividend under REIT rules until early next decade.