How to set the ringtone of iphone4s with mobile phone?

Step 1: Open iTunes, click File → Add File to Library, select the music file that you want to ring and confirm.

This song will appear in the music library. Right-click the song and choose Show Info.

Step 2: Select "Options" and fill in "Start Time" and "Stop Time" (within 40 seconds)-"OK"

Step 3: Right-click the song again and select "Create ACC Version"

Step 4: A song with the same file name but less than 40 seconds in duration appears. Right-click the newly created song and select Show in Windows Explorer.

Step 5: After entering, you will see a file named "Music Name.m4a" (if the file suffix is not displayed, click Tools → Folder Options → View, and remove the box in front of "Hide extensions of known file types"), change the format of "m4a" to "m4r", and select "Yes" in the pop-up window.

Step 6: Find Preferences in the Edit menu bar of iTunes, open the box in front of Ringtone in Common-Source, and then click OK.

Step 7: You can see the "ringtone" in the "database". Turn on the "ringtone" and you can see whether your file has been turned into a ringtone.

Step 8: Then turn on the iPhone in the device, select the ringtone, check the item "Synchronize ringtones", select "All ringtones" or "Selected ringtones", and then select "Synchronize".

Step 9: After the ringtone is successfully synchronized, the ringtone will appear in Settings-Sound-ringtone-Custom. To use this ringtone, just select it.

Finally, MP3 songs can only be played completely if the start time and stop time check boxes in the options are cancelled in the second step, otherwise, MP3 songs will only be played within the time you set.