About iPhone Ringtones
iPhone ringtones are files with extension .m4r. Iphone ringtones uses MPEG-4 file format. The default audio encoding is AAC (Advanced Audio Coding) which are supported from 8 to 320 kbps. M4R is a renamed AAC (M4A) file - it is similar to MP3 but compresses the digital audio files further. M4R ringtones are compatible with iPhone 4, iPhone 5 and iPhone 6 phones.