ESP32 4G LTE Portable Phone

I am building a 4G LTE phone which can send and recieve calls and SMS using the EC200U module, I am doing this as a challenge after building my arduino nano drone. My main aim through this project is to learn as much as i can, which is why I used the ESP32, which is something I am very new to. Additionally, taking a step beyond what other makers have done on platforms like instructables, i am adding a 32 GB SD card so I can store contacts, etc. This means i have to learn to use the SD.h library