The cellphone has acquired a host of new features in recent years, from text messaging to video. Now cellphone makers and wireless operators are shifting their attention to music, taking a swipe at the iPod and other stand-alone music players.

With high-speed cellular networks soon to be widely available, wireless operators are exploring new ways to deliver not only over-the-air music downloads, but also music videos, streaming and other new products tied to music.

While it remains to be seen whether consumers will take to buying music on cellphones, a variety of cellphone models with built-in MP3 players have reached the market or are about to be released. These phones still revolve around the PC for most of their music content, and compared with music players like the iPod from Apple Computer, most have smaller capacities for storing music files and fewer music features. But they also provide a new set of options for putting collections of music on devices that many people have to carry anyway.

The Sanyo MM-5600, available from Sprint (; $279.99 with a 2-year contract ), has a built-in media player that plays music files stored on a miniSD card. The included card has only 16 megabytes of capacity, which is small by music standards, and may hold only four or five songs. The phone can take cards up to 1 gigabyte (sold separately for about $105), which can hold about 240 songs of average size, and a U.S.B. cable is included for transferring files from PC’s to the card while inserted in the phone.

For listening to music, a stereo headset with a standard 2.5-millimeter jack is included, along with a built-in speakerphone with pretty good sound for music; songs can be played in random order and repeated. And as a flip phone, the MM-5600 can be closed while playing music, keeping the keypad and screen covered while volume controls are still available along the side.

The phone, which also has a 1.3-megapixel camera, works with Sprint’s optional music streaming services. MSpot Radio, for example, costs $5.95 a month and offers music in various genres. Not surprising for streamed music, though, the sound was slightly tinny in my tests.

The Sony Ericsson S710a is one of several music-playing phones that are available from Cingular (; $199.99 after rebate). It plays music files stored on an included 32-megabyte Memory Stick Duo, and can accommodate Memory Sticks up to 128 megabytes. As with the MM-5600 and most other cellphones, the S710a can play MP3 files but not copy-protected files like those sold at many online music stores.

To transfer files to the stick, a Memory Stick reader is included for plugging into a computer’s U.S.B. port. Files can be dragged from a computer or copied from CD’s using the Sony Ericsson Disc2Phone software, available for download at the company’s Web site. With the built-in Bluetooth wireless connection, files can be transferred to and from the card while it is inserted in the phone.

The S710a comes with a stereo headset and a built-in speaker with decent sound for music, and its music interface includes an equalizer to adjust bass and treble. The S710a is a swivel phone, and when music is playing with the phone in either the open or closed positions, the exposed keys and buttons can be locked.

A phone offered by T-Mobile, the Samsung P735 (; $499.99 with a 1-year contract), comes with a 32-megabyte Reduced-Size MultiMediaCard, also available separately in capacities up to 512 megabytes. The phone is more compact and rugged than the S710a, and as a flip phone that also swivels, it can be closed while listening to music. But on the P735, unlike some of the other phones, files cannot be transferred to the card while it is inserted in the phone, and a card reader is not included. The phone comes with a stereo headset, and songs can be sorted by name and date.

The Motorola V710 (; $99.99 with 2-year contract) is being offered by Verizon Wireless. It, too, uses a memory card for storage, but one is not included. The phone accepts TransFlash cards available in sizes up to 256 megabytes, and as with the P735, files must be transferred to the card before inserting it into the phone, and a reader is not included. And unlike some of the other phones, the V710 has a music interface that enables playlists to be created.

A number of so-called smart phones – cellphone-organizers with advanced software – have music-playing abilities as well, including the Audiovox SMT 5600, which uses Windows Mobile 2003 for Smartphone as its operating system. The device, available from Cingular ($199.99 after rebate) supports miniSD cards up to 1 gigabyte and includes Windows Media Player 10 Mobile, which can play copy-protected music purchased from some online stores like MSN Music and Napster. A stereo headset is included and a speakerphone is built in.

The Treo 650 from PalmOne, available from Cingular, Sprint and Verizon Wireless, can play MP3 files and RealAudio files with an included RealPlayer application. Music can be heard through a built-in speaker or headphones. For file storage, the Treo 650 accepts MultiMediaCards and SD cards sold separately in sizes up to 2 gigabytes.

And a number of phones on the way will offer more music features. The W800 Walkman phone, from Sony Ericsson, is expected to be available in August. A feature distinguishing the W800 is its music-only mode, enabling it to be used solely as an MP3 player while its cellphone transmitter remains off. Sony Ericsson estimates 30 hours of listening time in this mode.

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