When Windows Phone first launched in late 2010, there were a number of interesting and unique aspects to this system that really put it over the top. But generally speaking, the best news was that Microsoft had clearly learned the lessons of the past and reigned in some of the poorer decisions that hampered and then eventually doomed its previous mobile platform, Windows Mobile.

Key among these was a very detailed spec for what hardware had to be included in any Windows Phone handset, the level to which OEMs (wireless carriers and hardware makers) could modify the built-in software (which is to say, almost not at all) and the way the system handled software updates.

That latter bit, alas, became the center of some controversy.

In part 3 of my lengthy, 9-part Windows Phone review, I wrote that Microsoft had "reined in the wireless carriers' worst habit of all, and will be able to deliver software updates to all Windows Phone users going forward, and will in fact do so ... Microsoft is essentially ensuring that all Windows Phones will offer a high-value, consistent user experience, that its partners will not be able to screw up that experience, that users will be able to uninstall any partner software they do not want, and that in the future, the system will be upgraded with fixes and new features, and that the wireless carriers--for the most part--cannot prevent any of this from happening."

Ah yes. "For the most part." The truth, as I understood it then, was a bit more nuanced. At a reviewer workshop in October 2010, before the product launch, Microsoft's Joe Belfiore had told reviewers, "if a carrier wants to stop an update they can. But they will get it out on the next release." He added that updates were cumulative, which is true, but reiterated that "if one [carrier] doesn't get their testing done in time, the next push date comes and it goes out then."

These statements created what I now know to be a misunderstanding, where it was believed that carriers could block one Windows Phone update, but once another update appears, the carriers that blocked the previous update would be required to ship both.

Oddly enough, some took issue with even that explanation, arguing on their own blogs that Microsoft "owned" the Windows Phone software update process and thus could and would bypass carrier blocking all together. So I took it upon myself to set the record straight, like the well-intentioned goon that I am, based on what Microsoft had told me and other reviewers. The resulting post, The truth about Windows Phone 7, software updates, and carriers’ ability to block those updates, appeared on my Windows Phone Secrets blog in November 2011. It got me into a lot of trouble with Microsoft.

"Wireless carriers can block updates from reaching their customers," I wrote. "They can do so for one update cycle only, so if they do block an update, it will be automatically offered the next time a software update is released."

So here's the thing. My explanations of this process, in the review and in the separate Windows Phone Secrets blog post, were correct in that I accurately recorded and communicated what  Joe Belfiore, a Microsoft corporate vice president, said to reviewers. Microsoft, however, intended for the Belfiore conversation to be off the record, which, to be clear, is not what it says in my notes. But the important bit, fro this conversation, is that  I've since learned that this comment about software updates is not correct. It's not correct at all.

This issue is being revisited now, about 18 months after the fact, because Microsoft has delivered a couple of Windows Phone software updates that have not been delivered to customers on certain wireless carriers. This situation, of course, has resulted in some customer frustration, since we've all been lead to believe that carriers can only block a single upgrade.

Two of these, builds 7740 and 8107, are particularly important. Build 7740 is the first post-Mango build that  provides a handful of small fixes, and build 8107 fixes bugs related to SSL certificates, a disappearing virtual keyboard bug and privacy. And not surprisingly, customers on carriers that have not delivered the fixes in these updates aren't too happy about this situation.

As noted previously, the Belfiore description I've reported about how the Windows Phone software updating process works is incorrect. Yes, software updates are cumulative. But no, wireless carriers are not required to ship at least every other update. They can block software updates as they see fit. And, as is now happening, some carriers have in fact blocked two updates in a row.

Now, without getting too deep into "I told you so" territory, I did warn readers and Microsoft that the wireless carriers in general, and AT&T in particular, could not be trusted to do the right thing. But that was obvious. More problematic, perhaps, is this notion that one of the things that made Windows Phone superior is in fact not true.

On the flipside, the situation is still better than with Windows Mobile. Microsoft has engineered Windows Phone in such a way that wireless carriers have little legitimate reason to block most updates, and certainly the ones that some are currently blocking. Why they would do so is unclear. And there's always the chance that some of these companies will see the light and ship future updates--and thus all previously missing updates as well--at some point in the future. No promises, however.

As a matter of full disclosure, I should also relay Microsoft's official stance on this matter. The company tells me that it has never publicly communicated anything other than the fact that carriers could block as many updates as they wish. As important, it wishes to state that nothing has changed, and that Microsoft is not backing away from a previous position.

(What about the Belfiore comments I've widely quoted? Again, Microsoft claims the session he spoke at was under NDA, though my notes read that information in his talk could be freely published once Windows Phone shipped; remember, the reviewers workshop was from before the product launch. And I do believe I've quoted him accurately.)

"Some users may be disappointed at not receiving updates as soon as they're released, but it's true that Microsoft continues to deliver updates to carriers for acceptance and that mobile operators can't pick and choose updates in a way that creates holes in the experience," a Microsoft representative told me. "Once they accept an update--even if it's not the latest on the market--they also have to allow all receipt of all updates distributed before the update that's being pushed."

Anyway, I just wanted to set the record straight. I can't say that I miscommunicated this information previously, as I simply reported what was told to me and numerous other reviewers. But it's important that Windows Phone customers know what they're getting into and understand that, from Microsoft's perspective, nothing has changed. I think it's also important to note that, while this situation isn't optimal, Microsoft has clearly worked to improve its relationship with the carriers and convince them of the benefits of doing the right thing for customers. The carriers don't always do the right thing, in my opinion. But that's not Microsoft's fault, certainly.