Can I upgrade my phone even if I'm under someone elses plan?

Hi, to upgrade your phone you would have to be listed on the account as an Authorized User, which the Account Holder would have to add you on as. They can do this by calling Customer Care or going into a store. For the phone payments, there's no way to have that payment go directly to your card, it will automatically go onto the bill. However, a work around would be that every month before the bill is paid, you could log into the account online and make a payment for the amount of your phone's monthly payment.