Realtones, or music klingelton kostenlos, are audio recordings that have been converted into a format suitable for mobile phones. They are usually stored in popular digital audio formats, such as MP3 or AAC. For Android devices, the most popular format is OGG Vorbis. This container format is compatible with all kinds of music and helps you choose the perfect sound for your phone. However, be aware that many of these files can be copied and shared.