The Sony Ericsson S710a plays MP3 music files stored on an included 32MB Memory Stick Duo, and can accommodate Memory Sticks up to 128MB. The device cannot play copy-protected files such as those sold at many online music stores.
Motorola and Apple joined forces to produce the Rokr music phone, which holds about 100 songs.
Available from Sprint, the Sanyo MM-5600 has a built-in media player that plays music files stored on a miniSD card. A USB cable is included for transferring files from PCs to the card while inserted in the phone.
The Treo 650 from PalmOne can play MP3 files and RealAudio files with an included RealPlayer application. The device accepts MultiMediaCards and SD cards sold separately in sizes up to 2GB.