Neilsen reported on January 6 that 232 million Americans had a cell phone in 2011. That's just about everyone over the age of 13, which slows down growth. Not so in the emerging markets, where carriers such as Tim Holding ( TSU , quote ) and China Mobile ( CHL , quote ) are developing huge new customer bases.

Brazilian market regulator Anatel reported in January that Brazil added over 39 million mobile lines in 2011. Tim Holdings got a lot of those new customers, passing its rival Claro to take second place in the market with 64 million customers. (Being one of the leading sellers of iPhones didn't hurt.)

There will be more customers for Tim Holding as Brazil becomes more affluent, and this is reflected in the company's income statements: on a quarter-by-quarter basis, earnings have risen more than 140%.

China gained over 80 million 3G customers in 2011, according to the information and communications industry blog C114 . China Mobile captured 30 million of those customers, with rivals China Unicom ( CHU , quote ) and China Telecom ( CHA , quote ) not far behind. Smartphone customers are only 13% of China's 927 million mobile subscribers, so there are literally hundreds of millions of upgrades out there waiting to happen.

There is no shortage of good emerging market telecom plays out there in 2012. In addition to individual stocks, investors should also look at Guggenheim BRIC ETF ( EEB , quote ), which devotes a large part of its portfolio to China Mobile and other telecoms around the world.