Gateway devices can use dual cellular interfaces, each assignable to at least one of a plurality of network services, to provide reliable communications for client machines. A gateway device can use one of the dual cellular interfaces assigned to a first network service as a primary interface and the other assigned to a second network service as a hot backup interface. The backup interface remains connected to a cellular network while communications are routed on the primary interface. Accordingly, the gateway device can rapidly switch communications between from the primary interface to the backup interface. Applications, for example, for ATM payment processing, vending machine telemetry, point of sale payment processing, kiosk internet connectivity, remote monitoring and control, mobile or electronic health, and remote information displays, may run on the gateway devices, on servers, on user devices, or a combination of these devices.