Here is how I am able to use a mp3 file as a ringtone on my Verizon Envy cell phone.

First you need to crop the mp3 file down to less than 200kb. You can use Audacity (free) to do this.

I won’t go into the gritty details but you will need to open the file in audacity, crop it down to about 20 seconds and then save it as an mp3 at a bit rate of about 80kbs. Remember the new file need to be less than 200kb. You can be a little clever and crop the file in such a way that it will sound good looping.

Find the file on your hard drive in windows file explorer and make sure the size is less than 200kb. You may need to crop the file further and save it again. Change the extension of the saved mp3 file to .mid and copy it to your microSD card and place the card back into your cell phone.

On your phone browse to the new .mid file, it will be in your sounds directory,and select the option to send it. Send it to yourself. When you receive the call there is an option to save the file as your ringtone. That’s it!