One of the best sonnerie gratuite apps for Android is, which offers tons of options for ringtones, alert tones, and alarm sounds. Although it's an ad-supported app, it's easy to find what you're looking for and the selection is large enough that there's something for everyone.
Another popular way to get a custom ringtone is to download it from iTunes or an online music store. Then copy it to your phone as an audio file (MP3 or OGG format is usually best) and move it to the appropriate folder.
You can also make a ringtone from any music stored in your phone's music library. Just use a music editor to cut the audio, and you can turn it into a ringtone.
Then you can share it with others via email. You can either send the ringtone as an attachment or add it to a new email template. It's a simple and effective way to transfer your ringtones, so it's worth a try if you haven't already.
If you don't want to spend time creating a ringtone, you can try importing it from your computer. Most Android devices support music files in MP3 and OGG formats, but some devices also accept other formats.
