Callertone is a free Android app that generates custom ringtones for each of your contacts based on their phone numbers. You have the option to choose between an iMelody file or a simple monophonic sine synthesizer. With this app, you will be able to easily recognize who is calling you without even looking at your phone.

The app is easy to use and provides a great way to personalize your contacts. You will no longer have to hear the generic ringtones that come with your phone and can choose a unique ringtone for each contact. Additionally, if you want any specific changes or additions, you can easily contact the developer by sending an email to

Overall, Callertone is an excellent app for those who want to add a personal touch to their phone calls.