Client subscription - thingsboard via MQTT

I can publish data via MQTT to Thingsboard using Arduino and SIM800 how can I subscribe Thingsboard GSM as a client ,Is it possible to do so?

Hello, i’m trying to do this using a Telit Module 4G ME910C1-ww, but i can’t yet. Today i found it an AT command manual for connect the SIM7XXX to mqtt server and i try to do work. Maybe this can help you, the link for download is following: