Adding extra capacity to a Windows Phone 7 device via microSD card has been contentious since Microsoft launched its mobile platform last month.
Now, Engadget has discovered that using a microSD card in any Windows Phone 7 will prevent that card from being read from, written to or even formatted by any other device such as a PC, camera or printer.
Documentation for the Samsung Focus has revealed that a microSD card inserted into a Windows Phone 7 device is considered a ''permanent modification'' resulting in irreversible changes to the card. On an FAQ page for the Focus, Samsung states that once a card is added, ''it will no longer be readable or writable on any other devices such as computers, cameras, printers, and so on''.
''This includes an inability to format the microSD card for use in these devices,'' the page reads.
The page notes that even permanently removing a microSD card from a Windows Phone will not make it useable in other devices again.
Microsoft itself gives a similar warning via a Windows Phone support page, where it is stated that once added, a microSD card becomes part of the phone.
''The Windows Phone 7 operating system treats the SD card as an integrated part of the phone. This is in contrast to other devices, where you can use an SD card to increase the memory available to the device at any time or to transfer files to other devices,'' the page reads.
Meantime, AT&T has warned customers via Engadget that only ''Certified for Windows Phone 7'' microSD cards should be used in Microsoft's mobile devices. The reason, according to the mobile carrier, is that the Windows Phone platform ''requires a certified high-speed microSD card for optimal performance.''
At present, no such ''certified'' cards exist and no indication has been given as to when they will hit store shelves. According to Microsoft support documents, certification comes down to more than just ''a simple matter of judging its speed class.''
''Several other factors, such as the number of random read/write operations per second, play a role in determining how well an SD card performs with Windows Phone 7 devices,'' the page reads.
Engadget reports that random access speed is the key factor in determining if a card is compatible with a Windows Phone, and the cards best suited to the platform can reportedly only be bought in bulk by OEMs, leaving consumers between a rock and a hard place when it comes to beefing up the storage capacity of their Windows Phones.