Unable to subscribe to topics with sim800l on demo.thingsboard.io

I have been interfacing a sim800l gsm/gprs modem with thingsboard and it works well for publishing. while trying to subscribe for rpc commands, thingsboard does not acknowledge the packets. I did a simulation using a python script, it connects and is able to subscribe and receive rpc messages from the server. trying to do the same with the gprs module fails despite the fact that the packets are exactly similar. See attached image with packets from the wireshark capture (on the left) and my arduino-sim800 packets as they appear. FYI, the same code works with mosquitto for both subscribe and publish actions. I have tested it extensively with cloudmqtt.com. Please advise

Image at github thingsboard forum

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Hi Peter,
Were you able to get it working?

This issue is still pending

Did you manage ti get it working mbari. Thanks

has anyone managed to solve this?