Files that contain the .m4r file extension hold custom ringtones that have been created for the iPhone mobile device. These ringtones are created with iTunes and can only be created from songs that have been purchased from the iTunes Music Store.
Not all iTunes Music Store songs can be used to create M4R ringtones. In order to create an M4R ring tone from an iTunes song, the song must allow for M4R ring tone creation.
Some M4R files can be created with third-party software applications or may be downloaded from the Web. These files may not be copy protected and can be played on other media devices.
An M4R ring tone is automatically transferred to a user's iPhone when the iPhone is synced with the user's computer.
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