At the start of a keynote address on the second day of the MIX'11 conference in Las Vegas this week, a senior Microsoft executive apologized for his company's bungling of Windows Phone software updates. This very public mea culpa comes on the heels of a disastrous four months during which Microsoft and its partners have consistently missed deadlines for updating for the platform, angering customers. But Microsoft Corporate Vice President Joe Belfiore admitted to the problems up front in his keynote Wednesday and corroborated previous reports I've published about the snafu, before moving on to the day's other announcements.

"We are trying to get better about communicating all this," Belfiore said, referencing my key complaint about the Windows Phone team, which has operated in near silence since the launch of the product late last year. "One of the things we struggled with is that this involves us, OEMs [that is, device makers], and mobile operators, and it's hard to communicate what other people are doing."

Belfiore confirmed a number of things Microsoft had previously denied rather strenuously, including that its carrier partners could prevent Windows Phone updates from getting to customers. I first (accurately) described this situation in a November 2010 blog post and have been fending off the company's attempts to discredit these assertions ever since.

As I noted previously in WinInfo, the issue here is largely one of semantics: Microsoft doesn't like the use of the word "block"—as in, "carriers can block Windows Phone updates," which they can. And on that note, Belfiore never uttered that word during his public apology. But the results are the same: Carriers can block updates. And some are still blocking the first Windows Phone updates by holding them in a seemingly indefinite "testing" state.

"It's now rolling out," he said. "It's not available to everyone yet because some mobile operators are still testing it."

Given the carrier ability to, um, test updates, Belfiore says Microsoft faced a tough choice: It could hold up updates until the slowest carriers signed off, or just release them piecemeal, starting with unlocked phones, which get the updates directly from Microsoft. So it chose the latter approach—the lesser of two evils—which is logical enough. But as we head into late April, some of Microsoft's biggest carrier partners (most notably AT&T) have yet to sign off on what Microsoft retroactively named the "February update." It's still unclear when these carriers will do so.

Belfiore also made the fascinating admission that it was a surprise to the Windows Phone team that it had so many problems shipping such a small update. When it first started testing the first real software update, code-named "NoDo," it discovered that hardware makers had previously and quietly changed the configuration of some phones, which required Microsoft to ship an even smaller "pre-update" (that "February update") and a separate update for the Zune PC software to fix the problems. But then that initial release of the pre-update was so buggy that the software giant had to pull it for about a week to fix those new problems as well.

This is the company that ships software updates to more than a billion Windows PCs every month, by the way. But as Belfiore said, "phones are different. The OEMs do a lot more of the core OS code on phones than [with] PCs. Mobile operators play a role in testing and we are still trying to figure out the process for doing that."

But Belfiore says the Windows Phone team has implemented changes that should make future updates go easier. (Not would; Belfiore didn't make any promises.)  "We are optimistic we've gone through that learning process and won't face that in the future," he said. "We expect we are going to get these problems licked and have no problems in the future."

Of course, given the rough past couple of months, things can only get better. And Microsoft has only one more non-minor software update planned for Windows Phone: The Mango update that the company claims is still on track for a late 2011 release.