HW: SIM7020E NB-IoT HAT (from waveshare) + RPI3B + NB-IOT SIM from Vodafone CZ.
I am trying connect to NB-IOT network without success (automatic, manual), AT+COPS command show behavior that I don't understood.
AT
OK
ATI
SIM7020E R1752
AT+CGMI
SIMCOM_Ltd
AT+CGMM
SIM7020E
AT+GMM
SIM7020E
AT+CCID
898823900000********
AT+CPIN?
+CPIN: READY
AT+CFUN?
+CFUN: 1
AT+COPS?
+COPS: 0
Response isn't constant, most common value are listed.
AT+CSQ
+CSQ: 15,0
+CSQ: 14,6
+CSQ: 15,0
+CSQ: 14,7
+CSQ: 15,7
+CSQ: 16,0
AT+CMEE=2
Until this moment everything seems OK. This command in most case end with ERROR +-99% , other time return network list. I don't understood why AT+COPS=? return ERROR.
AT+COPS=?
+CME ERROR: operation not allowed
AT+COPS=?
+COPS: (1,"23003","23003","23003",9),(1,"23001","23001","23001",9),,(0-4),(0-2)
When I try manually connected to existing, non existing network (AT+COPS=1,2,"23003" AT+COPS=1,2,"23001" AT+COPS=1,2,"23099") with inserted Vodafone SIM card it will stop responding to any command until power cycle.
When I try commands without inserted SIM card (AT+COPS=? AT+COPS=1,2,"23003" AT+COPS=1,2,"23001" AT+COPS=1,2,"23099") it will respond CME ERROR: SIM failure or CME ERROR: SIM not inserted.
After problems with SIM7020E NB-IoT HAT, I tried using BC66-TE-B-KIT (devkit with BC66 chip) with same result. After while I found that I don't have configured Default PSD Connection Settings.
Required Default PSD Connection Settings on BC66:
AT+QCGDEFCONT="IP","nb.m2mc"
Required Default PSD Connection Settings on SIM7020x:
AT*MCGDEFCONT="IP","nb.m2mc"
After setting PSD connection to NB-IOT network start working.