We build an efficient and reliable data transport protocol on top of the Short Message Service (SMS). We conduct a series of experiments to characterize SMS behaviour under bursty, unconventional workloads. This study examines how vari-ables such as the transmission order, delay between trans-missions, the network interface used, and the time-of-day af-fect the service. We present the design and implementation of our transport protocol. We show that by adapting to the unique channel conditions of SMS we can reduce message overheads by as much as 50 % and increase data through-put by as much as 545 % over the approach used by existing applications. Although the transport protocol can provide efficient, low-bandwidth, moderate-latency data co...