Please be more specific with your question. If your asking how to pay by phone I recommend following the steps on the runescape website. If your asking how to get free membership, their is no simple way. Try goldfarming in-game and use that gold to pay for an upgrade here on sythe.
If your trying to get free membership by making someone else pay, it will work until they get their phone bill and cancel the charges made, then your account gets -credit and most of the time they will not allow you to use that method again.
Possibly he's just asking which countries support paybyphone.
In that case, the answer is: Australia, Belgium, Canada, France, Germany, the Netherlands, New Zealand, Switzerland, the United Kingdom, and the United States.