A mobile communication device has both an (expensive) long-range wireless network interface and an intermittently available less expensive network interface. Requests are received to communicate data items to and from remote computing devices. Each data item is associated with a transmission deadline and an urgency rating. A transmission schedule is created by assigning data items to specific times for transmission over the long-range wireless network interface, based on their deadlines and urgency ratings. When the lower cost network interface is not available, data items are transmitted according to the transmission schedule. When the lower cost network interface is available, data items are transmitted over the lower cost network interface, based on their positions in the transmission schedule, until it is no longer available.