Hello,
Thank you for contacting us.
Currently, Teltonika Telematics offers MQTT functionality with a special firmware version 03.27.07.Rev.520 which is compatible with FMx1 series trackers and also FMB001 and FMB010 for OBD II series GPS trackers. As for the FMx6 series, we have also a special firmware version 01.02.03_ID1028 that supports MQTT functionality.
Regards