It was only a matter of time.

Four months ago, Palm ( PALM) and Sprint ( S) released their new, smaller Centro smartphone.

A super-competent redesign of Palm's aging Treo, Centro became an instant hit. Sales figures released today are spectacular. Sprint's $99 price (along with a two-year service commitment) didn't hurt either.

It was exactly what Palm needed.

But Sprint's CDMA coverage area is limited -- to the U.S. What about the rest of the world. When would they be able to get a GSM version of the Centro?

The answer is -- starting today.

Palm and AT&T ( T)are announcing the world's first GSM Centro. I expect other GSM carriers around the world will follow suit shortly.

Once again, the great news here is that AT&T's GSM Centro will also retain the Sprint phone's $99 selling price (after rebates and after you sign a two-year AT&T service-plan contract.)

There are differences.

AT&T's Centro is a quad-band GSM world phone -- which uses AT&T's EDGE network for data. This means the new GSM/GPRS/EDGE Centro is slightly slower handling data tasks than Sprint's EV-DO Centro. On the other hand, the GSM Centro is just as fast as Apple's ( AAPL) iPhone using the same data network and GPRS/EDGE-based phones usually last longer between charges than phones on 3G networks.

On the lighter side, the other difference is that Sprint Centros come in black or red while the new AT&T Centros are available in Obsidian Black or Glacier White (with green accents). I know -- big deal! Actually it is. Centro has proven very popular with younger users as well as with women.

The phone itself makes and receives voice calls with aplomb, sends and receives text messages, handles personal and corporate email, lets you browse the Web with one of the best looking mobile browsers on the market, take and save photos and videos with the 1.3 MP camera and even listen to your favorite music through its built-in stereo speakers.

AT&T's Centro also comes loaded with a bunch of AT&T-centric applications and optional subscription offers such as AT&T Mail, XM Radio Mobile, AT&T Push-to-Talk services and MusicID song recognition

The handset is small but very usable. The keyboard is small but I find I make far fewer errors using it than with some larger keyboards on other smartphones. The phone worked flawlessly in the New York City area -- as well as everywhere in Barcelona while I was covering last week's Mobile World Congress.

The standard battery lasted nearly four days before needing to be recharged. And that was with using it to make and receive a lot of calls as well as browsing the Web almost constantly. My POP3 mail worked flawlessly. My corporate email account needs some sort of Byzantine security software which doesn't seem to be available for the Centro at the moment.

I really liked the Sprint version of Centro when I tested it a few months ago. I'm the first to admit that it's not in the same league as Apple's iPhone or Nokia's ( NOK) E90 Communicator but it is not designed to for that. It is supposed to be a very attractive option for people who would normally buy a run-of-the-mill dumb phone (opposite of smartphone?) for a hundred bucks. It offers them dozens of features they wouldn't get on similarly priced handsets.

The iPhone ($400 to $500) and Nokia's E90 sells for $1,100. The Centro is $99 and at that price is a smashing success.

As for data speeds, Palm and Research In Motion's ( RIMM) BlackBerry have figured out how to get the most out of mobile Web browsers that run on EDGE networks. The difference in speed when loading a WAP-based data page is minimal. If your device handles full HTML Web page you need faster data networks. It's why current, first-generation iPhones always searching for a faster Wi-fi connection. AT&T is currently in the process of rolling out faster networks.

But Palm's Centro is designed to a price -- it was made to bring thrifty users a smartphone experience they can actually afford. As long as AT&T keeps its data prices at a reasonable level the Centro brand will continue to thrive.
Gary Krakow is's senior technology correspondent.