Sorry about the inconvenience. I think you can try to upgrade the firmware of SIM900, please down load the firmware and tool (including how) from : garden.seeedstudio.com/images/8/ … d_tool.zip
Sorry about the inconvenience. I think you can try to upgrade the firmware of SIM900, please down load the firmware and tool (including how) from : garden.seeedstudio.com/images/8/ … d_tool.zip