I'm 15, And i wanna know how i can build up my credit so i can get a cell phone with T-Mobile?

You can write them an I. O. U. :O)

When I was 18, I signed up with T-Mobile (back then, the company name was VoiceStream). Because I had absolutely no credit at all, they had me pay a $200 security deposit, which they gave back to me a year later. I've been with them for 9 years now. I don't know if they would allow you the same type of thing if you are under 18 years of age, but I think it would be worth asking them about it.

I think that the fastest way to get credit would be to ask a family or friend that could add you as a user to their current credit card. Make sure they have good credit themselves. Of course, tell them you will not be using the credit card all you need is to be added as an authorized user to build your own credit...make sure the credit card company asks for your social security as well. This way their credit history for that particular credit card would appear on your credit. Make sure they have never been late on their payments. By the following month your credit should be showing up. Good Luck! (A good credit card to try this with would be Citibank credit card, they for sure can add you as a user. I have done this before). After you get the phone they can remove you from the credit card.

to build credit you need a credit card, a mortgage, a loan, or something that requires you to make payments on it on a regular basis. so you cant build credit till you are 18

Oh geeze... First off, tell your mom she needs to read a personal finance book (don't really do that) Second, was she serious?

you have to be 18 to be approved for credit

lol