No, it is not tool issue or USB to serial converter. I am guessing something wrong with the module.
One question, I am going to use SIM800c in my design. I watched your video about 2G issue, I guess it will be good for few years though. Despite that, is there any issue do you think of? Should I go for Telit or quectel?
Where do I buy these modules? I could not find them on element14 or on Digikey.
And Do I need to know APN for every network provider if I want to change sim card then this would be very painful? There must be some way as in cellphone, there are no such settings to connect with internet.