Sorry I just saw your reply now. What firmware version are you using of the SIM7000A? (AT+CGMR) We’re using B03 and B04 and the AT commands in SIM7000 Series_AT Command Manual_V1.05 are supported. You can find software on the web to upgrade your modem firmware using the USB port on the modem.
Below is a copy of one of our sessions where we send data and get a response back from the server. We loop until we get a CSQ of < 31 (there’s a bug in the 7000 firmware where a CSQ of 31 means it’s still connecting to the base station). Then we verify we’re registered (a 1 or 5), then we get the base station info using the AT+CPSI command, open the socket and send/receive the data. I hope this helps!
+CPSI: LTE CAT-M1,Online,310-410,0x3D84,56866834,243,EUTRAN-BAND12,5110,3,3,-20,-117,-80,5