The reason for the excitement yesterday was the release of Windows 10 Mobile build 10586.29 to the Lumia 550, Lumia 950 and Lumia 950 XL including on AT&T, which came as a surprise. Interestingly, the update itself is rather ho-hum with no new features, but a few important under the hood fixes. Most users are reporting better standby battery life, improved Bluetooth compatibility and a more enjoyable Edge experience. But let's be clear: there is nothing dramatic, dire, or security-related about this update that would require an emergency release. No, this is a standard cumulative update released on Patch Tuesday just like it was for the Windows 10 desktop. Interestingly, both desktop and mobile were updated and are now on the same build. That is also another seminal moment as Windows 10 is truly just one operating system. Best VPN providers 2020: Learn about ExpressVPN, NordVPN & more So why did carriers not hold up the update? Microsoft has been a bit coy on the process and carrier involvement. The only statement they have on the matter is one from earlier in the year: "Microsoft is working closely with mobile operators to leverage their testing and our flighting to meet and exceed current quality bars. We will use their input but will decide when to send the updates out based on input from mobile operators and our Windows Insiders." The standard reading of that is Microsoft can bypass carriers although those same carriers do have a seat at the table too. However, that statement didn't go so far as to sideline them completely either. The other part of this is whether or not this was a one-time exception for AT&T or will we see a regular cadence of updates. What's different in Windows 10 Mobile

Yesterday, Windows and Devices Executive Vice President Terry Myerson also Tweeted this bit: "Big day, first update worldwide (and more to come) to all phones running #Windows10 - same build as PC!" The "more to come" is the important part, but it is not the crux of why things are now different with Windows 10 Mobile. Here is why this OS is dissimilar from Windows Phone 8.1. A few people knowledgeable about the matter tell me that the radio stack is basically "blackboxed" in Windows 10 Mobile. As one person explained it: "…the non-radio stack has been almost completely isolated from the radio stack (before the BSP contained a lot more "system" components); carriers need to test and certify updates that touch the radio stack, but MS can do the rest without their involvement." Another person also mentioned how BlackBerry's BB10 OS was the first to do this, but now Windows 10 Mobile also shares the same OS architecture.