Windows Phone 7 Allegedly Breaks MicroSD Cards

Windows Phone 7 devices support additional storage via MicroSD but making use of that capability has become problematic. Users who attempt to re-use MicroSD cards they purchased for older phones are in for a nasty surprise. Insert a legacy MicroSD into a Samsung Focus, and the device may crash, slow considerably, or suffer data corruption. Worse, there's no going back—an incompatible SD card that's been plugged into a non-compatible handset can no longer be used the original reader.

According to Microsoft, SD cards should only be inserted by the carrier and only certain specific SD cards are reported. WP7-compatible SD cards will ship with a specific logo advertising said support, but according to AT&T: "This information is not currently marked on any microSD packaging in market today. As a result, we are advising customers to delay purchasing an external microSD card until the cards identified as 'Certified for Windows Phone 7' are available commercially or in AT&T stores."

Microsoft claims that SD cards must support certain transfer speeds and random read/write rates to qualify for certification, but that's not the whole story; the official Windows Phone 7 documentation explains the rest. When storage is added to a Win 7 phone, it performs the following tasks:

  • It reformats the SD card
  • It creates a single file system that spans the internal storage and the SD card.
  • It locks the card to the phone with an automatically generated key.
Once the SD card is integrated, removing it will kill all phone functionality save for emergency calls; the phone will only function if the original SD card is reinserted. If a non-compliant SD card is used, Microsoft states that apps may not start properly, application transition time could be impacted, and the phone might become unresponsive.

Now with fewer features

There are two other significant limitations:
Integrating a Phone with a Different Windows Phone 7 Compliant SD Card: If your phone already has an SD card and then a different Windows Phone 7 compliant card is integrated with the phone, you will lose any data that was stored on the phone, including any applications that you installed from the Marketplace hub. Examples of data that might be stored on the SD card include manually linked contacts, start customizations, and data that applications do not store remotely.

Adding an SD Card to a Phone with an Empty SD Card Slot: If you purchase a Windows Phone 7 device with an empty SD card slot and you add an SD card to the phone after you start it for the first time, the phone will continue to work properly, but it will not recognize the SD card. The phone will not save applications or files to the SD card.To use an SD card with the phone, a Windows Phone7 compliant card must be integrated with the phone in one of the scenarios described above in the section. [SD cards can only be added when the phone is first initialized or after a full factory reset. Similarly, it's possible to remove an SD card when reformatting the phone, but said card will never work in another device.
Who Thought This Was A Good Idea?

Every phone, camera, or MP3 player that heretofore supported microSD has treated the additional space as a discrete space that can be moved between devices and holds multiple types of data. Microsoft's decision to flip this model on-end and treat external storage capacity as additional irremovable internal storage is baffling to say the least. According to Microsoft's documentation, users don't even have the option to use a microSD card in the traditional manner. If users aren't supposed to add their own microSD cards, it might be a good idea to prevent them from doing so. Just a thought.

Microsoft has, at least, decisively beaten Apple in one area. While the iPhone also lacks external storage options, it doesn't lock SD cards into particular devices or refuse to save data to them. Faced with the absence of a feature, the boys of Redmond worked night and day until they came up with a feature that's worse than having no feature at all.