cellphone cards

[.]

Hi again,

Back where I live we use cards to recharge credit in your cellphone in case your prepaid account runs without money, this can be found in denominations of 10, 20, 50 pesos (local currency). Now these thingies come with a ten digits number or so I can't remember and I don't have one handy, so basically you call to a local *151 follow the instructions, type this number and voila' credit charged.
I'm pretty sure that there is a way to emulate the algorithm so I can release these numbers and use my cell for free.
Any ideas? If you need extra info please ask, I can even go and get a card, unfortunately scanning is not an option :s and there're not on Google, I've searched already...
 

[Chuck Sanders]

When I was living in Europe everyone had this same type of phone basically, I only met one person with an actual bill me later contract.. I too would like to figure out how they do this since I still have my sim cards, I would just put euros into a box at the petrol station and they would print out a code to use, I forget if the box was hooked up to a phone line or not.

[.]

When I was living in Europe everyone had this same type of phone basically, I only met one person with an actual bill me later contract.. I too would like to figure out how they do this since I still have my sim cards, I would just put euros into a box at the petrol station and they would print out a code to use, I forget if the box was hooked up to a phone line or not.

I don't think so, here are printed already you can get them almost everywhere even supermarkets, they come with a film and some ink cover that you have to scratch to look at teh actual number.
That's why I'm saying, it has to be an algorithm!!!

[Chuck Sanders]

They have those here too for pre-paid cellular service, you have to scratch to reveal the number.. I believe they have to activate them at the register