Nokia 6126 / 6131 / 6133

I have a Nokia 6126 not made anymore, and I am trying to set a mp3 music file in my phone as the callback. I click the tone,"use tone" then "set as callback tone" then i tried calling my phone on other various phones and every time its just common ringing no callback . Is it just the phone, the format of the file? or do i have to actually buy the callback and pay monthly fees