Google's new stock Android Google Play Edition phones are unlocked GSM devices, but a quick word of warning: That doesn't necessarily mean they'll work well on the network of your choice.
Generally speaking, an unlocked GSM phone can run on either AT&T or T-Mobile (or any of the prepaid providers that utilize their networks) in the U.S. But there's a lot of fine print involved -- stuff about spectrum, bands, and all sorts of other confusing numbers most of us never think about.
Google's last unlocked device, the Nexus 4, was designed to work properly on any of those options. But the two new Google Play Edition devices are different; they aren't Nexus phones and they weren't designed with Google's close involvement in order to have wide-reaching compatibility. They're essentially just existing hardware with new software in place.
So what's that mean for you? Here it is: If you're using the HTC One Google Play Edition on T-Mobile in an area where T-Mobile doesn't yet have LTE service (which, let's face it, is most of the country), there's a good chance you'll be disappointed with the data speeds you get.
The reason: The HTC One Google Play Edition, unlike the T-Mobile-specific (non-Play-Edition) HTC One, does not support the bands needed to use T-Mobile's HSPA+ AWS service. The official word, as it was explained to me by Google, is that the phone supports HSPA+ service on T-Mobile's 1900MHz band but not the carrier's 2100MHz band, and the HSPA+ AWS service requires a combination of 1700MHz and 2100MHz compatibility in order to function.
Like I said, lots of confusing numbers. But the translation is that in many parts of the country, the phone won't be able to get the nice 21 to 42 Mbps HSPA+-level speeds that devices like the Nexus 4 enjoy.
If you spend most of your time in an area where T-Mobile already has LTE service, this won't matter to you, as the phone works fine with T-Mobile LTE. There are also some areas of the country where T-Mobile has moved its HSPA+ service onto the 1900MHz spectrum; those places should also be okay.
But for many of us, the One Play Edition won't be a viable option with T-Mobile at this point. When I put my T-Mo prepaid SIM into the phone, for instance -- a SIM that regularly gets me speeds around the 18 Mbps mark with a Nexus 4 -- I crawl along with barely-usable Edge-level speeds. That's clearly not gonna work.
This limitation is specific to T-Mobile, by the way; the phone will work fine across the board with AT&T. And the Galaxy S4 Google Play Edition, due to the radios present in the particular model Google decided to use, should work fine on either HSPA+ or LTE with either AT&T or T-Mobile.
When it comes to the Google Play Edition of the HTC One, though, if you're a T-Mobile customer, you may want to see where your city stands in terms of LTE support and 1900MHz HSPA+ support before you take the plunge. Otherwise, you could be in for a disappointing data speed surprise.