Hello Arun,
gsm_cmd(sms); //here you are giving Enter value(That is not required)
tx_data(0x1A); //this is necessary
After typing message give only CTRL Z (0x1A) no need of Enter value(0x0D)
i didnt understand what is “AT+CSMS=1”;
you can give
AT <enter>
AT+CMGF=1 <enter>
AT+CMGS=”xxxxxxxxx” <enter>
Type a message then <CTRL+Z>