Are you trying to do the project which controls devices using GSM module. At the user end we have a app that shows all connected devices and allows us to controls them. At the other end we have GSM module with relay connected to a switch board.
I need to design a rest api based website. Which will have user interface that can be used by user to turn things on and off. That will remove the need of mobile app as everyone can open website in any internet device. While Api service will be used by client iot devices to fetch the data from website.