This chapter presents a reference model for mobile payments, discusses the design alternatives for the configuration of payment security in mobile terminals. Mobile payments are financial exchanges that involve at least one mobile terminal. Mobile commerce is a convergence of banking, telecommunications, and information systems. Payment Instructions to the point-of-sale terminal or to the network server can be sent with one of several text messaging protocols: Short Message Service, Subscriber Identity Module (SIM) Application Toolkit/Universal SIM, or Unstructured Supplementary Service Data. M-PESA is an operator-centric payment service in Kenya. Safaricom controls every stage of the process with banks acting as depositories of the funds. Card networks and banks have agreed to lower their fee for payment processing to encourage the shift away from cash and checks. When a user makes a payment using Google Wallet, Google actually pays the merchant and then processes the transaction with the customer’s payment instruments.