Patent ID: 8082211

Claim:
A method of purchasing an item from a merchant by a user over a wireless telecommunications network using a mobile telephone handset, said method comprising: formulating a draw request message at a subscriber identification module (SIM) of said handset that includes a purchase amount of said item; sending said draw request message over said telecommunications network from said SIM of said handset to a payment server computer associated with said merchant; generating a first cryptographic signature at said payment server computer using a first cryptographic key shared between said SIM and an issuer; sending a debit message from said payment server computer to said SIM in said handset including said first cryptographic signature and an approval to debit said SIM by said purchase amount; verifying said first cryptographic signature at said SIM using said first shared cryptographic key; debiting a stored-value application of said SIM by said purchase amount; sending a debit result message from said SIM to said payment server computer that includes a second cryptographic signature, said second cryptographic signature being generated using a second cryptographic key shared between said SIM and said issuer, said second cryptographic signature uniquely identifying said SIM and indicating that said stored-value application of said SIM has been debited by said purchase amount; verifying said cryptographic signature from said SIM using said second shared cryptographic key; and sending a confirmation message from said payment server computer to said merchant indicating that said SIM has been debited by said purchase amount, whereby said merchant releases said item to said user.