The present invention provides a method for conducting a transaction that includes receiving a pseudo account identifier that corresponds to a primary account identifier. The pseudo account identifier may be received at a portable wireless device and may be generated by a remote server computer. The portable wireless device can receive the pseudo account identifier over a first network and provide the pseudo account identifier to an access device. The access devices generally comprises a reader that can receive the pseudo account identifier, and thereafter send a message to request authorization of a transaction. The authorization request message may include the pseudo account identifier and is sent to a payment processing network. The authorization request message is sent to the payment processing network over a second network. The payment processing network may then process the authorization message and return a response that indicates if the transaction is authorized or not.