Dividend investing is popular again. Investors have taken to heart Jeremy Siegel's studies, which show that higher-yielding stocks tend to offer greater returns over time than low- or no-yield stocks.

The highest dividend yields can be very tantalizing. As long as a stock yielding 15% doesn't lose value, you'll make 15% in one year! In more cases than not, however, an astronomical yield is a bad sign for a stock. Since dividend yields and stock prices move in opposite directions, a high yield usually means that investors have begun to worry about the business and driven down its stock price.

Dividends are not guaranteed; you need to make sure that a business is generating enough cash to pay its dividend, or your investment could be disastrous.

A few months ago, I ran a screen for the highest-yielding telecom stocks, and it got such a good reception that I'm doing it again this quarter. The only limitations I set are that I'm considering only telecoms, and they must have a market cap greater than $1 billion.

Here are the top 25 highest-yielding telecoms the screen produced.

  Company Name Market Cap (millions) Dividend Yield
1 Cellcom Israel (NYSE: CEL)

$2,950

11.7%
2 Telefonica (NYSE: TEF)

$108,958

10.6%
3 Telecomunicacoes de Sao Paulo (NYSE: TSP)

$14,635

10.5%
4 Partner Communications (Nasdaq: PTNR)

$2,524

9.9%
5 Alaska Communications Systems (Nasdaq: ALSK)

$394

9.9%
6 Philippine Long Distance Telephone (NYSE: PHI)

$9,934

9.7%
7 Frontier Communications (NYSE: FTR)

$8,012

9.3%
8 France Telecom (NYSE: FTE)

$59,426

9.2%
9 Portugal Telecom (NYSE: PT)

$9,584

8.7%
10 Consolidated Communications (Nasdaq: CNSL)

$563

8.3%
11 Vivo Participacoes (NYSE: VIV)

$17,680

8.0%
12 Windstream (Nasdaq: WIN)

$6,635

7.7%
13 CenturyLink (NYSE: CTL)

$24,226

7.2%
14 Turkcell Iletisim Hizmetleri (NYSE: TKC)

$12,373

6.9%
15 USA Mobility (Nasdaq: USMO)

$338

6.5%
16 KT (NYSE: KT)

$8,392

6.4%
17 Telecom Corp. of New Zealand (NYSE: NZT)

$3,717

6.1%
18 Telecom Italia (NYSE: TI)

$26,277

6.0%
19 SK Telecom (NYSE: SKM)

$10,358

5.9%
20 NTELOS Holdings (Nasdaq: NTLS)

$808

5.8%
21 AT&T (NYSE: T)

$179,496

5.7%
22 Chunghwa Telecom (NYSE: CHT)

$26,375

5.7%
23 Verizon Communications (NYSE: VZ)

$100,093

5.5%
24 Vodafone Group (NYSE: VOD)

$137,644

5.5%
25 Telefonos de Mexico (NYSE: TMX)

$15,593

5.4%

Source: Capital IQ, a division of Standard & Poor's.

These stocks are a good place to start your research, but they're not formal recommendations. Remember, their seemingly irresistible yields could be ticking time bombs, so do your own due diligence. Also make sure you diversify your picks across various sectors. As investors relearn every decade or so, you never want to put all your eggs in one basket -- no matter how tempting the dividends are.

For a basket of some high-yield some dividend opportunities, get The Motley Fool's five-page free report: 13 High-Yielding Stocks to Buy Today.