Over at XDA, emjee87 has been compiling a list on what microSD cards are reported to work with the Focus/WP7. This is because AT&T has gone back and forth on if SD cards should be installed and if so which ones, etc. Remember that this list is a work in progress so we need to see what happens as the cards get filled and used more often. You can also see that people are reporting issues, with some cards not working at all, some slowing down over time and some causing reboots so this is a real issue. So bear in mind that Windows Phone is only a few days old in the US this has to be treated as a rough guide but it’s better than what AT&T has told us (which is nothing):

Confirmed Working(Data remains after soft reset):
Kingston 4GB Class 4
Kingston 8GB Class 4
Kingston 32GB Class 4
Microcenter 16GB Class 2
SanDisk 8 GB Class 2
SanDisk 16GB Class 2
SanDisk 16 GB Class 6
Currently Unstable/Unsure:
SanDisk 32 GB Class 2
Confirmed Not Working(Data gone after soft reset):
A-Data 4GB Class 6
A-Data 16GB Class 6
Lexar 16GB Class 6
Transcend 8GB Class 6
Transcend 16GB Class 6

For my two cents, I’m using a Kingston 32G Class 4 without problems but I haven’t loaded it up with more than a gig or two of music so far. Let’s keep their work going and add your results to the XDA thread and we’ll follow it here as well.

By the way, here’s MS’s warning on the issue but the don’t provide a list of working cards aside from the preinstalled ones.


  1. I have been running a Kingston 16GB class 4 in my focus with no issues. It showed 22.12 GB of total storage and 20 GB of usable storage before I started loading it up with music and apps. I powered the phone up first to the start screen. Then powered it down added the memory than powered it up using the sequenced stated in the instructions.

  2. Also using the Kingston 16GB Class 4 without problems so far, have about 22gb of space and 15gb free still. I have reset several times and no issues.

  3. Don’t have a Focus but just want to get this straight. The replacable SD card loads on top of 8GB internal storage + the device RAM. I thought the cards you are referring to “replaced” the 8GB memory. Guess I was wrong, with numbers like 22.12GB total storage and a 16GB card.

    So the 8GB internal + the replacable card (different sizes/classes/manufacturers) are seen by the device as a single drive. That’s a pretty good trick. Make sure you backup.

  4. @jimski: yup there’s 8g on board (a fancy ass high speed internal memory card in fact) so what you put in gets added to the 8 on board and then they all get combined when you format the sd card

  5. Have been using a transcend 16g class 6 for a few days. I have about 10g of music on it now and have seen no problems so far.

  6. I bought 2 Samsung Focuses (or is it Foci)… Anywho,… my wife and I had our 16gig cards from our last phones HTC Pure. The cards were the cheapest we could find… Duracell brand. Not sure if Duracell is still selling these… Either way, they work just fine. From the start, no fussing… Just re-set the phone and off they went.

  7. I can verify the Kingston 16GB Class 4 card works. I have just over 15GB free out of 22GB total. This is probably the best card for the money that is stable with the Focus.

  8. @Brett P: @Brett P: I tried a transcend 16g class 6 and it worked alright until the phone was turned off and back on (soft reboot), this caused the phone to show only 16mb of memory instead of the 24gb installed.

  9. @Brett P:

    No longer works. Phone crashed with transcend 16gb class 6. Phone reset itself and reports only 15mb of memory. Took card out and did reset and still only 15mb of memory. Reset all 3 differnt ways and only 15mb of memory. Had to take phone back to ATT and get replacement. I am now waiting for certified memory.

  10. Lexar 16GB Class 4 will work, until you play games like The Harvest, or anything that does a lot of reading/writing. At which point the phone will reset and all your data will be lost.

  11. Guess through all this we are going to find out why SanDisk cards typically cost more. The only brand I would ever use for a phone or other data access intense applications. The bargain brands are fine for moving stuff from device A to device B, but I wouldn’t suggest storing your wedding or first born’s pictures on them.

  12. I would never leave my trusted files on a memmory card of any sort. Lucky for me Microsoft has that cool thing where it sends my pictures to Skydive as I take them… Plaing games on my cheap card,.. no issues yet. I have 3 movies and about 8 gigs of music 1 gig of pictures and some podcasts. No problems yet, no resets no lost data. Only thing is I wish I would have waited to buy a 32gig card before adding all this junk to my phone…. Now I have one nasty job ahead of me if I do update my card…

  13. […] Samsung Support, Engadget, MobileTechWorld, MobilityDigest […]

  14. Kingston 32gb class 4 does not work. It performs exactly as microsoft says it will. Applications become unresponsive at times, the phone slows down, and every now and then it will reboot itself.

  15. Yesterday tested Lexar 32GB class 10. After the first hard rest the card was recogniezed byt he device and gave a read of 37 GB. after the first soft reset. it went down to 16 GB. steps repeated three times with the same outcome

  16. Yesterday I bought PNY 16 GB Class 4 and works pretty well. Only difference noted so far is that when reinstalled some games, specifically Fruit Ninja, sometimes when you swipe the finger for a combo the screen kindda freezes quickly then comes back, and such occurrence wasn’t happening when I was using the SanDisk 8 GB Class 4.System shows I have 22.02 Total Storage and it’s pretty much enough for what I need.

  17. @Bruce: Try PNY 16 GB Class 4. Got it yesterday@Best Buy for US$32 and after installed it my system shows 22 GB available. I previously thought about getting PNY 16 GB Class 10 but wasn’t sure if it would work. But when you get your current SD out and install the new, the previous really won’t work. It doesn’t even show up on the Windows Explorer, so basically it becomes trash, so careful when picking the cards.

  18. Hi All..One of my friend bought Samsung Focus fo me from US.As it is having 8 GB internal memory,is it necessay fo me to put 32 GB external memory card.Since it says once memory card inserted should not be removed.Can anyone help me out

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