code for connection Arduino nato to Sim 800l

hi I need a to transform a code used for wifi connection (esp8266) to GSM sim800l connection (using Arduino nano). In code are two sensors, one for humidity and temperature and another one for weight. the sistem should work like: send SMS with,,0'' --> receive message with the data's. send message with ,,1'' --> receive message from 1 hour to 1 hour from sensors. Sent message with ,,2'' all the above commands to be cancelled. The code must include multiple APN's (to allow you to change the SIM card without rewritting the code)