Experimental setup consists of USB/TTL converter (1), attached to terminal emulator, ESP8266 Wi-Fi module (2), Arduino UNO board (3) and 100 Ohm resistor (4)*.
The steps of the experminent are as follows: 1) Start UDevTerm terminal emulator 2) Start Wi-Fi access point on terminal emulator 3) Attach USB/TTL converter (1) to Android Device OTG USB port, connect USB/TTL converter to terminal emulator 4) Connect Arduino UNO USB port to power 5) Configure USB/TTL converter connection with terminal emulator
Arduino UNO ESP8266 module sketch
6) Wait till ESP8266 module connects to UDevTerm terminal emulator Wi-Fi port, then configure Wi-Fi connection 7) Establish Bluetooth connection between UDevTerm terminal emulator and Teraterm PC terminal emulator (configure Teraterm to transmit CR+LF after each message) 8) Create bridge connection between Android Device OTG USB port and Bluetooth port 9) Exchange messages between Teraterm emulator, sending messages to TTL port of ESP8266 module in form of AT commands over Bluetooth, and UDevTerm terminal emulator, connected with ESP8266 over Wi-Fi. First a message 14 characters long should be entered in Teraterm that ESP8266 module is waiting for over TTL port to send it over Wi-Fi. (Modify Arduino UNO module sketch to enter your access point name, password, etc.)
(*) Research showed that in order to be able to send messages from Android terminal through TTL port to ESP8266 module, that is already connected to Arduino UNO board, an additional 100 Ohm resistor (4) is required. Otherwise, ESP8266 module will not response to messages sent to it through TTL port from Android terminal.