Comunication with GSM via UART

[mamaxam]

Hello members,

I need to send commands to my GSM module via UART (RX/TX) TTL pins on my ESP board.
Here https://www.letscontrolit.com/wiki/inde ... _Reference
I found information about "Serial (TTL) <command> Send commands using serial (RX/TX). Just type the <command>"
But I do not know, how to send AT command to my device and receive OK status.
can someone help me?

Thanks, Milan.