Open-electronics have designed great compact device based on Atmega2560 programmable with Arduino. It is a GSM remote control with 2IN/2OUT pins, DTMF key, gate control and thermostat activated remotely.
Device (called TiGiDino) uses Simcom SIM900 GMS module. So remote can be operated by sending SMS. Also control can be performed with call. If number is recognized the relay will be activated. Also DTMF enables to control remote with multi-frequency telephone tone.