1. Dial *983*889*1# to enter TTY full mode.
   Note: TTY requires a fully compatible TTY telephone. TTY Full mode will transmit and receive TTY characters.
   
2. Dial *983*889*2# to enter VCO mode.
   Note: VCO mode will receive TTY characters but transmit by speaking into the microphone.
   
3. Dial *983*889*3# to enter HCO mode.
   Note: HCO mode will transmit TTY characters but receive by listening to the receiver.
   
4. Dial *983*889*0# to reset the phone to standard mode.
   Note: Standard mode will restore regular calling functions.