I use the card in my Siemens SL45i (firmware 54) to store MP3s. The phone is working still problems with the card. The Card-Explorer shows a total of 244.07 MB usable space. Madness, unlike the originally supplied 32MB card! The MP3 player of mobile phones plays without stutter of the card, even with constant bitrate or 320 kbps (MP3s created with EAC and LAME). Well, the latter was only a test, because with 320 bit rate, the MMC is full quickly! The price of the card is great, I have before ordering price comparison operated on the Internet, which in some cases come to hefty shipping costs with other providers. All in all 5 stars.