For iPhone:
Step 1: Find Your MP3 Ringtone
Start by selecting your favorite MP3 ringtone. You can grab these from reputable sources like Zedge, MyTinyPhone, or even create your own from music tracks you already have.
Step 2: Convert MP3 to AAC Format
iPhones use the AAC format for ringtones. You'll need to convert your MP3 file to this format. You can do this using various online converters or software like iTunes.
Open iTunes and find your MP3 file. Right-click on it and select "Create AAC Version." This will create a duplicate in AAC format.
Step 3: Change the File Extension
Locate the newly created AAC version of your ringtone. Change the file extension from ".m4a" to ".m4r".
Step 4: Add to iTunes
Drag and drop the newly renamed ".m4r" file into your iTunes library.
Step 5: Sync with Your iPhone
Connect your iPhone to your computer and select it within iTunes.
Under the "On My Device" section, click on "Tones".
Drag and drop your newly created ringtone into the Tones section.
Step 6: Set Your New Ringtone
On your iPhone, go to "Settings" > "Sounds & Haptics".
Tap on "Ringtone" and select your newly added custom ringtone from the list.
that's the easiest way to install free MP3 tonos de llamada for your iPhone and Android