Exchange-traded funds offer a convenient way to invest in sectors or niches that interest you. If you expect the world's telecom giants to thrive over time as our planet's population grows and the proliferation of smartphones, tablets, and other communication devices continues, the iShares S&P Global Telecommunications ETF (NYSE: IXP) could save you a lot of trouble. Instead of trying to figure out which companies will perform best, you can use this ETF to invest in lots of them simultaneously.

The basics
ETFs often sport lower expense ratios than their mutual fund cousins. The iShares ETF's expense ratio -- its annual fee -- is a relatively low 0.48%. It recently yielded a satisfying 4.9%, to boot.

This ETF has performed rather well, topping the world market over the past three, five, and 10 years. As with most investments, of course, we can't expect outstanding performances in every quarter or year. Investors with conviction need to wait for their holdings to deliver.

With a low turnover rate of 13%, this fund isn't frantically and frequently rejiggering its holdings, as many funds do.

What's in it?
Some global telecom companies had strong performances over the past year. Sprint Nextel (NYSE: S), America's third-biggest wireless carrier, soared 29%. It hasn't paid a dividend since 2007, as it has been struggling, but there are catalysts investors can be hopeful about, such as the upcoming release of the iPhone 5, which is likely to sell briskly. Still, the company has significant debt, and it's unclear how successful its unlimited data plan will be, though some are quite optimistic that paired with an iPhone, it will draw many consumers.

CenturyLink (NYSE: CTL), meanwhile, jumped by 26%. America's third-largest telecom company, it recently yielded 6.8%. The company has been streamlining itself, cutting down from five to three operating divisions. CenturyLink has invested in some big acquisitions, buying Qwest and SAVVIS last year, with the latter bringing in cloud-computing exposure. Bears worry about the company's heavy debt and not-so-promising landline business, but it has been developing other income streams. Its free cash flow has been growing, too. Management recently explained that it's expecting investments in converting from copper to fiber-based connectivity to pay off in the long run.

Other companies didn't do as well last year, but could see their fortunes change in the coming years. Spain-based telecom giant Telefonica (NYSE: TEF), for example, sank 33%, in part due to the financial crisis there. Things aren't that bleak, though, as it actually generates much of its revenue from Latin America, where economies are healthier and growing faster than much of Europe. It's getting some positive attention from Wall Street (along with negative attention), and has temporarily suspended its dividend, which had been yielding more than 11%.

France Telecom (NYSE: FTE), meanwhile, shed 19%, and recently yielded a whopping 12% -- though it plans to reduce its payout next year. It needs to expand beyond Europe, where markets are fairly saturated at this point. It's doing so in sub-Saharan Africa, actually, where its majority-owned Orange division has enjoyed subscriber growth rates above 20% for its mobile service. It carries a hefty debt load, too.

The big picture
Global demand for communication services isn't going away any time soon. A well-chosen ETF can grant you instant diversification across any industry or group of companies -- and make investing in and profiting from it that much easier.

The mobile revolution is still in its infancy, so it's tough to get a handle on which companies will succeed over the long haul. For our analysts' take on it, check out our free report, "The Next Trillion-Dollar Revolution," which reviews a compelling company at the forefront of the trend. Hundreds of thousands have requested access to previous reports, and you can access this new report today by clicking here -- it's free.