Do cell phone companies do credit checks online?

I want to buy a cell phone plan from Tmobile online. Im 19 and have no credit, but I do have a debit card and make a good amount of money for someone my age. I DO NOT want a prepaid phone. I know cell phone companies do credit checks, but if Im buying the phone & plan online how would they go about doing this? If they decide to deny me (b/c I have no credit history) will they email me or send me a letter or something saying no...or will they say yes but then ask me to pay a deposit online with the plan? Thanks