This is the first device that personalizes your landline telephone with songs, movie sound-clips, or comedic greetings that play when someone calls. If you have caller ID, you can use the included PC software to assign unique ringtones to friends, family, and unwanted 800 numbers so you can identify a caller by ear. Ringtones are downloaded from your PC to the unit via the included USB cable. The player connects between your home's telephone jack and your telephone so it can read the caller ID information, but it will not interrupt normal service. The device holds up to 10 free ringtones and comes with credits for additional downloads from a library of thousands of popular songs and audio clips from the manufacturer's website. A slot for a Flash SD memory card (not included) expands storage up to 1GB (250 ringtones). Requires Windows Vista, XP, 2000 SP4, 256MB RAM, 2x CD-ROM drive, and 275MB free hard drive space. 3" H x 5" W x 1" D. (2 lbs.)