The only condition for free use is a credit line. Personal YouTube videos and streams are free even if monetized (promoting a company or paid client work needs a license).
A slightly unusual ringtone, Ver. 1. Both feature phones and smartphones come preloaded with plenty of tunes and tones, so we are not sure how much demand there is, but at least it will not sound like anyone else's phone - feel free to use it as a ringtone. Silence is built into the file to make it loop; adjust the silence length to change the loop interval to your liking.