The final quarter of the calendar year is always good for gadget sellers -- particularly wireless carriers selling sleek phones and new plans. This past holiday season was exceptionally good to America Movil (NYSE: AMX), a massive provider of wireless services to dozens of Latin American markets.

America Movil added an impressive 10 million net new subscribers across its markets in the fourth quarter, bringing its total base of wireless subscribers to 153.4 million. Strong customer uptake in areas in Brazil, Peru, and Mexico helped the company report a 28.5% increase in service revenue, boosting quarterly net revenue to $7.89 billion. And net profits increased 50% year over year to $1.47 billion.

For the full year, America Movil delivered double-digit subscriber growth across all its operating regions, including greater-than-60% growth in Peru. In total, its wireless subscriber base has grown 23% since last year. Most of the growth has been organic, but the company also added 768,000 new customers in Jamaica and Puerto Rico by acquiring Verizon's (NYSE: VZ) local operations there.

Even in the competitive U.S. market, the company's TracFone subsidiary grew its subscriber base by 20.5% to 9.5 million. Americans have been flocking to low-priced, prepaid plans purveyed by the likes of Leap Wireless (Nasdaq: LEAP) and MetroPCS (NYSE: PCS), which are similar to TracFone's offerings.

Even nationwide giants like AT&T (NYSE: T) and Sprint Nextel (NYSE: S) are getting an increasing number of new customers on prepaid plans as the market approaches saturation. And though the average revenue from TracFone's prepaid base (ARPU) dropped 12% to $12 per month, America Movil still returned $135 million in operating earnings from the subsidiary this year, double the amount from last year.

The results cap a strong year for America Movil, surpassing the growth levels that even I expected. That continued success also led the company to increase its share buyback authorization by $1.4 billion, following an extraordinary $3.2 billion dividend payment last November.

Even if future subscriber growth slows from this level, America Movil remains a compelling investment at these prices.

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