And it’s unfortunately not very good news.
According to Microsoft’s Charlie Kindel, the company does not support end users upgrading the storage in their Windows Phones with micro-SD. This is a carrier feature, and if the carrier is going to sell such a device, the intention is that it is they, and not the end user, that adds, tests, and supports that configuration.
The issue, apparently, is the micro-SD card format. The cards are unreliable and inconsistent, even between batches made by the same manufacturer, and in Microsoft’s tests, there was no way to “certify” that any would work properly. “Even with high end cards, we have seen wild differences in IO and performance,” he said. “There is just no standardization there.” Put simply, if you expand the storage in a compatible Windows Phone device, it may work, and it may not.
“In most cases, users will have issues,” he told me. “Most cards are of poor quality, and there’s no way we can control that or recommend a certain type of card. If you happen to get a good card, with the right performance and IO characteristics, it will work reliably. But even a bad card will appear to work at first, and the device will boot.”
That, of course, is where the fun starts. If you have a bad card, you’ll notice horrible, unreliable performance, slow app boot times and performance, lock-ups, and random reboots.
“It’s not intended to be user serviceable,” he said. “The carrier does it and supports it.”
As for the “why’s” behind the design, Kindel said that the alternative was two file systems, where the user would have to choose where to put stuff, and micromanage file management. That is not what Microsoft wants for Windows Phone.
Kindel’s advice is for users to check with the carrier first. And Microsoft is going to provide me with AT&T contact information so I can get a statement from them as well. For now, at least, it looks like those that wish to expand the storage in a Focus or other compatible device are on their own.