We are currently testing the BG96 module with Japan’s telecommunications carrier, NTT docomo.
We are using two types of SIM cards:
- SIM A：IIJ（a Docomo MVNO operator）
- SIM B：ImoT（Docomo IoT Plan）
eDRX is enabled on the BG96 with a 10.24-second cycle.
Below are the current consumption waveforms.
With SIM A, the RRC connection is released approximately tens of seconds after startup, and the device then transitions into the expected eDRX cycle.
After about 2 minutes and 30 seconds, the device briefly returns to RRC Connected state, but this is not a significant issue.
However, with SIM B, the RRC connection is never released, resulting in consistently high current consumption.
All AT command settings are identical between the two SIMs, except for the APN configuration.
Here is a portion of the initialization sequence:
SND,AT
RCV,AT
RCV,OK
SND,ATE0
RCV,ATE0
RCV,OK
SND,AT+QCFG="risignaltype","physical"
RCV,OK
SND,AT+CMGF=1
RCV,OK
SND,AT+CSCS="IRA"
RCV,OK
SND,AT+COPS=1,2,"44010"
RCV,OK
SND,AT+QICSGP=1,1,"mopera.net","","",0
RCV,OK
SND,AT+QICFG="recvind",1
RCV,OK
SND,AT+CEREG?
RCV,+CEREG: 1
RCV,OK
SND,AT+QIACT?
RCV,OK
SND,AT+QIACT=1
RCV,OK
SND,AT+QCFG="urc/ri/ring","off"
RCV,OK
SND,AT+QCFG="urc/ri/other","off"
RCV,OK
Do you have any insights or possible reasons why the ImoT SIM (Docomo IoT Plan) maintains RRC Connected and doesn’t release the connection, even with eDRX enabled?
Any suggestions or similar experiences would be greatly appreciated.