Hey,
Thank you for your response. I actually tried that mode as well, but the results were the same. If it may give better idea of what could be wrong this is what I tried to use in order to send AT commands:
1. using echo “AT” > /dev/ttyUSB0 115200 and after that using cat to read the port I had no response.
2. using minicom with both settings with hardware flow control on and off (on both sides – pc and modem) no response.