The nation's #6 wireless carrier with 4.6 million subscribers, MetroPCS attracts people by offering unlimited calling at low rates. Right now, they're available in nine states, but they're spreading; most notably, they're starting service in the New York and Boston metro areas soon. Major Metro markets (so to speak) include Wilmington-Philadelphia-Trenton, DE-PA-NJ, Los Angeles, San Francisco, Atlanta, Detroit, Dallas, Orlando and southern Florida.

MetroPCS's expansion comes because they bought new spectrum two years ago. Like T-Mobile and like Cricket, another smaller carrier, MetroPCS is expanding on the new 1700 Mhz band. So while Metro uses CDMA and BREW technologies just like Verizon Wireless does, they have a different set of phones to support their unusual network frequency.

Metro doesn't do contracts; all of their plans are month to month, and some of them are great values. While plans start at $30/month, we recommend starting with the $40 plan, which includes unlimited calling from your home city to anywhere in the lower 48 states, voice mail and unlimited texting. For $50/month, you get unlimited picture messaging, e-mail, IM, WAP browsing, and directory assistance. The "big four" carriers generally charge at least $100/month for similar unlimited plans.

I tested four Metro phones in Philadelphia, PA and Trenton, NJ. Traveling around Mercer County, NJ, I found good Metro coverage throughout Trenton and along the Route 1 corridor up to the Quaker Bridge Mall, just as advertised on Metro's coverage map.

Metro has a low-end range of phones to go with their low-cost plans. You won't find any smart phones here. Rather, you'll find simple, voice-centric, low-cost phones. There are no free phones, because the phones aren't subsidized by expensive two-year contracts. The fanciest phone I tested is the Samsung R450 Messager, a texting phone with a QWERTY keyboard. Almost all of Metro's phones so far are 2G, accessing the Internet at relatively slow CDMA 1X speeds of about 100 kbits/sec. Metro told me that the Philadelphia market, where I tested, uses the 3G EVDO system, but there are no 3G phones available there yet. Dallas and Detroit also have EVDO, but only with one 3G phone, the Motorola Z6m.

Speaking of Sprint and Verizon, Metro's MetroFlash program is a neat way to bring former Sprint and Verizon subscribers into the fold. Available only in some cities (the ones not on the new 1700 Mhz system), MetroFlash will connect a wide variety of Sprint and Verizon feature phones to Metro's system for $40 per phone. That includes even fancy phones like the LG EnV and Samsung Instinct.

Metro offers some innovative data services on their phones. Each of the four phones I tested came with a premium 411 program, powered by V-Enable, that lets you speak a city name and business name, and then gives you the results back on your phone screen with a map. I found that far more usable than the traditional "voice" 411. The phones also run Mapquest Mobile for mapping; Loopt, for social networking with other Metro users; and very basic IM and e-mail programs. A brand new service, Screen-It, will display caller ID with the calling party's name, just like on a land line. On their WAP home page, meanwhile, they have a direct link to the interesting Slifter comparison-shopping service, which lets you compare prices for any item at local stores near you.

There's a catch, of course. If you travel outside Metro and Cricket coverage areas (the two carriers offer free roaming on each others' networks with some plans), you'll pay 50-80 cents/minute for roaming. Even within those coverage areas, Metro's signal may not be as strong as titans like Verizon. Deep within Philadelphia's 30th Street train station, I had zero bars of Metro but two bars of Verizon signal; this was likely because Verizon's 850 Mhz signal penetrates buildings better than Metro's 1700 Mhz.

The best balance of price and performance came from the Samsung MyShot R430, a basic camera phone that gives you clear calls and ease-of-use in a small, friendly package. Metro's top-of-the-line phone, the Samsung R450 Messager, is a good choice for heavy SMS text users because of its QWERTY keyboard. The other two phones didn't fare quite as well as the Samsungs. The ZTE C79 is an interesting flip phone from a company new to the US market, but I found some of its features felt rough. The inexpensive Nokia 1606, meanwhile, didn't deliver very good voice quality.

MetroPCS isn't the only smaller carrier offering low-cost, unlimited wireless. The competing carrier Cricket, which covers many smaller US cities, has a similar phone lineup but is now delving into 3G as well. I'm reviewing a bunch of Cricket phones right now, and I'll report on them soon.