No doubt about it, the international telecom sector has been hot lately -- particularly the wireless variety. Stock in China Mobile (NYSE:CHL) is up 54% in the last three months, and Russia's VimpelCom (NYSE:VIP) is up 27% in the same time frame. Even Vodafone (NYSE:VOD) has registered a gain of 30% year to date.

Mexico's America Movil (NYSE:AMX) has been on a tear as well, surging 42% so far this year on growth in subscribers in markets such as Mexico, Brazil, and Argentina. In fact, growth in the company is one of the catalysts behind Carlos Slim's rise to the status of the world's richest person, according to Forbes.

It's easy to see why the stock has grown so dramatically. Spun out of TelMex (NYSE:TMX) in 2000, America Movil had limited operations outside of Mexico, as subscribers there made up almost 90% of its total base of 10.1 million. Now, Mexico accounts for only about one-third of the 137.2 million subscribers in 16 countries, thanks to aggressive expansion both organically and through acquisitions.

At the time of the spinoff, wireless penetration in Latin America was only 13%. While it stands at more than 55% now, many developed countries support penetration rates of more than 80%. One example is the U.S., where, despite a mature market, operators AT&T (NYSE:T) and Verizon Wireless -- a joint venture of Verizon Communications (NYSE:VZ) and Vodafone -- routinely add more than a million new customers each quarter. There are still millions of potential subscribers America Movil can capture in Latin American countries.

I've already chimed in that I think China Mobile, while a great company, is not a great stock at its current valuation of roughly 34 times earnings. In fact, many international telecoms are getting too expensive. But America Movil trades at a much lower 24 times earnings. While America Movil looked much better in the mid-$50s last month, I think the company is still a worthy consideration for investors looking to tap the growth of emerging wireless markets.

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