Hi Arnold 1) The GPRS AT commands can be found on the datasheet of teh SIM868 (https://download.mikroe.com/documents/datasheets/sim868-hardware-design-v1.000.pdf) 2) The access to the gpio need to add something like that: http://canada.newark.com/piface/shim/gpio-duplication-board-raspberry/dp/83X91...