An audio file in the Files app cannot be selected directly as an iPhone ringtone. A common Apple-supported method is to import an editable audio file into GarageBand and export it as a ringtone.
- Open GarageBand and create an Audio Recorder project.
- Switch to Tracks view and import the audio file from Files.
- Trim the project to the section you want as the ringtone.
- Return to My Songs, touch and hold the project, then choose Share > Ringtone.
- Name and export the ringtone, then assign it immediately or select it later in Sounds & Haptics.
Protected subscription-streaming tracks generally cannot be exported as custom ringtones. If the audio is too long, trim it before export or use GarageBand’s offered shortening option.