A method of delivering instructions to a mobile user device connected to a network, the method comprising the steps of: at a first application gateway receiving an application for execution by a client application on the mobile user device; translating the application into instructions in a form executable by the mobile user device; sending a message including the instructions to the client application at the mobile user device; the instructions causing the client application to verify the instructions, interpret the instructions, interact with the mobile user device or the user, and send responses back to the first application gateway or another application gateway; wherein the application received at the first application gateway defines: one or more addresses of respective mobile user devices specified for receiving the application, steps to be performed on the one or more mobile user devices, the address of an alternate gateway server, if any, to which the response from the client application should be sent, with the address being the originating application gateway if no alternate address is given, how the response data returned to the gateway specified for receiving the application should be processed by the gateway, and the communications methods that are to be used to send the instructions to the mobile user devices and to receive the response data, and wherein the instructions sent to the mobile device are configured to include a divert command to divert a response to a second application gateway and wherein to receive the response data includes to check the integrity of the response received from the mobile user device by calling an Application Program Interface of a first application gateway when the response is diverted by the user device to a second application gateway. at a first application gateway receiving an application for execution by a client application on the mobile user device; translating the application into instructions in a form executable by the mobile user device; sending a message including the instructions to the client application at the mobile user device; the instructions causing the client application to verify the instructions, interpret the instructions, interact with the mobile user device or the user, and send responses back to the first application gateway or another application gateway; wherein the application received at the first application gateway defines: one or more addresses of respective mobile user devices specified for receiving the application, steps to be performed on the one or more mobile user devices, the address of an alternate gateway server, if any, to which the response from the client application should be sent, with the address being the originating application gateway if no alternate address is given, how the response data returned to the gateway specified for receiving the application should be processed by the gateway, and the communications methods that are to be used to send the instructions to the mobile user devices and to receive the response data, and wherein the instructions sent to the mobile device are configured to include a divert command to divert a response to a second application gateway and wherein to receive the response data includes to check the integrity of the response received from the mobile user device by calling an Application Program Interface of a first application gateway when the response is diverted by the user device to a second application gateway.