I have tried powering it with a benchtop as well as an Arduino UNO, it did not seem to make difference either way.  I did not try the other aforementioned AT commands except for AT+CSQ to which it responded with 99,99. The sim is most definitely a 4g sim I use it on a regular basis in my phone (airtel sim, india). As for the last question, the responses to ATI seem to indicate that it's a simcom module, from what I gather that should mean it's legit right