Answer: They build an iPhone.

Top Cell Phone Manufacturers' Estimated Revenues Compared to Apple's

In the cell phone game, the Apple iPhone only accounts for 8% of the total industry revenue, but 32% of the total industry profit. How they managed this feat is quite simple. They pull in a 40% operating margin, in an industry that averages only 7.5%. The next most profitable company in the industry, RIM, only takes in 20.7% operating margin.
[ iSmashPhone.com ]

• By early 2006, thirty countries had exceeded 100% per capita cell phone usage
• In 2006 there were about 241 million mobile phone users in the United States — or, approximately 80% per capita mobile phone penetration
• According to industry estimates, it won’t be until 2013 that the US will top 100% per capita penetration
• Two thirds of mobile phone users are “active users of SMS text messaging.” What does that translate to? Approximately 1.8 billion people are actively texting today
• Globally, there are twice as many active users of SMS as are active users of email
• In the U.S. alone, roughly 300 billion text messages were sent in 2007
• SMS is typically read within an average of 15 minutes after receipt and responded to within 60 minutes
• While 65% of e-mail is spam, less than 10% of SMS is spam
• 19% of text messagers say they use text messaging as a means of communication between themselves and colleagues
• 62% say they use text messaging to communicate with friends
• 55% say they use it to communicate with their significant others

Source: Mobile Marketing Watch

Additional mobile marketing statistics