Make your phone as bridge between USB serial port and TCP/IP Network.
TCP Client SSL-UART
USB serial port devices supported:CDC devices ,CP210X,FTDI devices(FT232,...) ,PL2303,CH34x
You can send data from serial port (uart) to the internet with both TCP,UDP. Your phone can as Client or Server or both,Supports multiple concurrent connections.
You can run application as server or background service.