Hello Vyacheslav Frolov , I think my app use 7-bit-mask. I have set AllDataBits =yes, but I have problem to receive fax. Can you help me? Many thanks 2020/09/08 00:21:20.015 COM38(e):84c --> 7 bytes of binary 2020/09/08 00:21:24.640 COM38(e):84c --> AT+FTH=3 2020/09/08 00:21:24.640 COM38(e):84c <-- { 0d 0a 43 4f 4e 4e 45 43 54 0d 0a ..CONNECT.. } 2020/09/08 00:21:26.250 COM38(e):84c <-- { 0d 0a 43 4f 4e 4e 45 43 54 0d 0a ..CONNECT.. } 2020/09/08 00:21:26.531 COM38(e):84c <-- { 0d 0a 4f 4b 0d 0a ..OK.....