Traditionally, cell phone carriers in the United States have liked to control not only what goes into their phones but also how those phones are used. So when we learned today that T-Mobile and Sprint have signed onto the Open Handset Alliance (OHA), the group that will develop applications for Google's new Android mobile phone platform, immediately I was intrigued. Could a U.S. carrier really be joining a group that will encourage free and open use of a mobile phone? Yes Virgina, it is true. And Sprint can't wait to get started.

Though neither carrier would reveal specifics on when we'll see Android-powered phones, or even if they exist yet, Sprint spokesman Scott Sloat said that Sprint is committed to promoting the free and open environment that Android will bring. "We're in favor of customers dictating what they want [on their phone]," he said. "This will open up the platform to developers."

Pardon me, but I'm still a bit in shock that I'd heard those words from a carrier. To his credit, Sloat acknowledged that the broad support for the OHA from both carriers and manufacturers does mark a big shift in how the U.S. wireless industry has progressed up until now. But he said it's also a natural next step for a company such as Sprint to take. He expects Android to be a natural fit for the company's existing 3G network and its coming WiMax network. "We want to give customers a true Internet experience on their phones," he said. "The end game is all about increasing wireless-data usage."

So if a better mobile Internet (and more wireless data minutes) is the whole point, T-Mobile's participation is interesting. T-Mobile is the only major U.S. carrier to lack a 3G network and the carrier remains mum on when we'll see one. In a Google-sponsored conference call this morning, Qualcomm CEO Paul Jacobs emphasized that 3G applications will be huge part of Android. Google Chairman and CEO Eric Scmidt added that Android will run well on all existing cellular data networks, but it's not surprising that 3G will be the sweet spot.

So will we see T-Mobile formally roll out a 3G network before the middle of the next year, when the first Android devices are supposed to appear? Unfortunately, when I called a T-Mobile spokesman this morning, he still wouldn't say. Nor would he elaborate on how T-Mobile USA will use the Android platform. Apparently, that's being left up the German parent company for now.

I don't know why AT&T and Verizon Wireless haven't signed on to the OHA. I expect that AT&T has its hands full with the iPhone and that all that customer freedom may be a bit much Verizon, which has always been one of the most control freak carriers. But in any case, look for my News.com colleague Maggie Reardon to answer that question.

Of course the biggest question in all of this is whether T-Mobile and Sprint really will honor the open source spirit of the platform? Will they really let consumers use their cell phones as they please? As was said during this morning's conference call, carriers offering an Android-powered phone will be able to alter and restrict the phone as they wish. So, while Schmidt such a scenario is "highly unlikely," it would be possible for a carrier to offer a completely locked Android handset. But Sprint's Sloat doesn't think that will happen either. "It would go against the grain of [Android] to turn around and limit its use." Nicely put, Scott. Let's just hope it stays that way.