Great question — answering as the UphillTech team:
Have you verified that you are registered with your operator properly? You can do this by sending a AT+CREG? Regarding the AT+COPS error message. It seems like you aren't sending enough parameters. AT+COPS=<mode>,[<format>,<oper>[,<AcT>]] Are you trying to manually select an operator rather than letting the modem take the default operator setup with the SIM card?
Full answer by Matt Aldridge: https://stackoverflow.stackexchange.com/a/7315877 (CC BY-SA 3.0).
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