My idea is to automate the process of keeping in touch with my server in a portable and internet independent manner. The most optimal solution in my case is an SMS Gateway/Relay because I travel a lot and I want to eliminate the situation when I do not have internet access (WiFi or SIM). The 3G USB Modem is the best solution because I can keep it in my home wall plate, and the little ones cost around 7 Euro (Huawei K4305) in my town.
My problem is that I didn't found a custom firmware with a web shell integrated to build the php file that request the information from my server API and send via sms to my mobile number. (I don't want online SMS Gateways like SMSGlobal)
Is there a "BinWalk / Firmware Mod Kit" friendly FW version or projects related to this? My knowledge in reverse engineering is poor. Thank you for your attention and time!