A mobile telephony device comprising: a mobile communication interface for communicating via a communications network; a contactless communication interface for communicating with a point-of-sale terminal; a first processing portion comprising a secure element constituting a first application environment; and a second processing portion comprising a second application environment external to the secure element, wherein the second processing portion comprises a payment application for conducting an EMV payment transaction, the payment application having a first operative state wherein said payment application is enabled to conduct said EMV payment transaction, and a second operative state, different to said first operative state, and wherein the payment application is operable: i) responsive to receipt of a session key via the mobile communication network, to be configured into said first operative state, and thereafter ii) responsive to receiving a request from the point-of-sale terminal for an application cryptogram, to perform an authorisation process, wherein the authorisation process is arranged to: generate an application cryptogram on the basis of the received session key; and transmit the generated application cryptogram to the point-of-sale terminal via the contactless communication interface. a mobile communication interface for communicating via a communications network; a contactless communication interface for communicating with a point-of-sale terminal; a first processing portion comprising a secure element constituting a first application environment; and a second processing portion comprising a second application environment external to the secure element, wherein the second processing portion comprises a payment application for conducting an EMV payment transaction, the payment application having a first operative state wherein said payment application is enabled to conduct said EMV payment transaction, and a second operative state, different to said first operative state, and wherein the payment application is operable: i) responsive to receipt of a session key via the mobile communication network, to be configured into said first operative state, and thereafter ii) responsive to receiving a request from the point-of-sale terminal for an application cryptogram, to perform an authorisation process, wherein the authorisation process is arranged to: generate an application cryptogram on the basis of the received session key; and transmit the generated application cryptogram to the point-of-sale terminal via the contactless communication interface. i) responsive to receipt of a session key via the mobile communication network, to be configured into said first operative state, and thereafter ii) responsive to receiving a request from the point-of-sale terminal for an application cryptogram, to perform an authorisation process, wherein the authorisation process is arranged to: generate an application cryptogram on the basis of the received session key; and transmit the generated application cryptogram to the point-of-sale terminal via the contactless communication interface. generate an application cryptogram on the basis of the received session key; and transmit the generated application cryptogram to the point-of-sale terminal via the contactless communication interface.