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Windows Phone 7 Samsung Focus microSD card issue FAQ: why reformat and add ing normal micro SD cards won't work and more

Updated on August 11, 2011


The following is an unofficial FAQ documenting the issues around the Windows Phone 7 Samsung Focus microSD card. It cites available sources in the news media.

If you have additional questions or information regarding this issue, feel free to add them in the comments.

Samsung Focus, a Windows Phone 7 mobile
Samsung Focus, a Windows Phone 7 mobile

What Is the Issue with Samsung Focus?

The main problem with Samsung Focus, a Windows Phone 7 mobile, is that regular microSD cards you can buy in a store, such as Best Buy, Radio Shack, and so on will not work or cause the phone to react unpredictably, with random slowness / lag, glitches, and so on.

Some reported that if one had to restart the phone the storage was no longer recognized. Others found the storage to be unrecognized, and one must use internal "reset" to restart the phone to make the storage recognizable. The manual itself gave a special power up sequence but it doesn't seem to do anything useful.

What's worse, the card was automatically reformatted by the phone, no matter what's on it before, with absolutely NO confirmation. You lose all data on it, and because it won't be recognized on anything else, the card cannot be returned.

So far, this is only a problem on Samsung Focus, which has a user-accessible microSD slot. The other Windows 7 phones, such as HTC HD7, do not have user accessible slots.

AT&T store employees were reported told NOT to sell microSD cards to Samsung Focus owners, and to warn them NOT to try to add microSD cards themselves, until Microsoft and Samsung certify some microSD cards, and/or send some automatic patches.

MicroSD card
MicroSD card

What Sort of Problems with the microSD card are there with Samsung Focus?

If you insert the microSD card into the Focus, it may not work properly with the phone. Once the microSD card is removed, it is NOT visible on most microSD readers. It is not visible in a card/media reader. It is not visible in a camera (that take microSD cards). It is not readable in other phones that take microSD cards. It's not only unreadable, it is invisible. You can't even reformat it.

Engadget's Chris Sigler and team found that the microSD card used in Samsung Focus is visible once inserted into a Nokia N8, a Symbian phone. Turns out Symbian is one of the few places that fully implemented the "secure" portion of "secured digital", i.e. SD card.

Now the situation is clear: Windows Phone 7 used the secure features of SD card, which made the card not visible or readable to any other reader. The card is "paired" with the phone. A device that fully implemented the "secure" features of SD card can see and reformat the card, but cannot read the content of the card. Only the original device can.

Class 4 MicroSD High Capacity (SDHC) 4GB card from Sony (no, this is not compatible with Samsung Focus, just for illustration purposes)
Class 4 MicroSD High Capacity (SDHC) 4GB card from Sony (no, this is not compatible with Samsung Focus, just for illustration purposes)

What Class of microSD Card Do I Need for Samsung Focus?

That's the problem. There is no such card available.

The cards available to the public, as certified by the SD Card Association, are class 2, 4, 6, and so on. They specify the minimum sustained write speed. For example, class 2 can write data at 2 megabytes per second. Class 6 can write data at 6 megabytes per second, and so on. However, these are "sustained write speed", whereas Windows Phone 7 wants to write random access, not sustained.

Microsoft apparently contracted with a microSD card maker to make some special microSD cards just for Windows Phone 7 makers for the OTHER phones that DOES have the necessary random access performance. So far it is not known who is the manufacturer, and all their cards so far are used inside the phones. None are available to the public.

AT&T issued a statement that they and Microsoft are working on a certification process, but so far no card is available to the public, as of Thanksgiving, 2010.

SanDisk originally listed many microSD cards for the Samsung Focus, but withdrew them all from its website as of November 17, 2010, according to engadget.

If Card is Paired With the Phone, Why Is It Removable?

Microsoft's original phone specs actually said that the memory should NOT be removable, according to InfoWorld article. According to Microsoft design specs, the memory should be fixed, similar to iPhone's fixed storage. Later some phone makers want to customize the models to use microSD cards, so Microsoft worked that into the phone specs, but the memory was never meant to be easily removable.

So in other words, Windows Phone 7 really needs 2 microSD card slots... One "fixed" for the phone itself, and one for removable storage, but somehow that wasn't done. Where do you assign the blame? Depends on who you ask.


Hope this clears up some of the questions regarding Windows Phone 7 Samsung Focus microSD card problems.

If you have further questions or comments, please add them in the comments.


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    • profile image


      7 years ago

      I inserted a Class 10 32 GB SamSung MicroSD and followed the Samsung Focus instructions for insertion POWER UP sequence. It formatted the SD in less than one second after I answered the power up format questions. I have 36GB total available and have reloaded my music, calendar, apps, etc. So far not one issue. I was hoping I would have 48GB available after I added the 32GB. The 32 GB cost me $44.00 and tax. I should have bought the 16GB card in retrospect but alas they had no Class 10 left in 16GB by Samsung. Other brands may also work but class 10 seems to be a winner.

    • profile image


      7 years ago

      I have been using a Patriot C10 32GB micro SD (PSF32GMCSDHC10-BC) and had no stability problems at all.

    • profile image


      7 years ago

      i had the chip in my card, it did nothing at all, it did not even read it.

      as soon as i insert it the phone began to act more odd then it already was.

      it would not stop beeping kept freezing and was giving me a hard time about battery.

      a friend tecy said the windows phone is terrible, to remove card "despite what instruction says" and reset the phone.

      so i did.

      now it is always saying my cell is charging and it likes to beep non stop.

      by far this is the worst phone i have ever had, and i used to own the LG chocolate.

      so that should tell you something.

    • kschang profile imageAUTHOR


      8 years ago from San Francisco, CA, USA

      You need to borrow someone's Nokia phone and use it to reformat your MicroSD, as explained in the article. Good luck to you.

    • profile image


      8 years ago

      Yeah, this was just insane. The guy in the AT&T store, while I was picking out accessories, formatted my 16 GB Micro SD Card, it was laid to waste, cannot reformat it, cannot use it in any other device as the 2 point text on the micro SD card slot foretells. Then, to add insult to injury, I searched high and low for the "approved card" after discovering there was actually only ONE APPROVED cadr. I was lucky enough after 8-10 phone calls to find one for $93. It made the phone reset and "brick" about every other day. So now I have another $200 in cards original 16 GB that worked fine for 3 years in my Palm Treo Pro (probably the best Windows Mobile device ever) and my brand new 8 GB card. My advice, DO NOT USE THE SD SLOT in the Samsung Focus!


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