RE: Automatic dual mode scan

user93921 — Wed, 25 May 2022 12:07:45 GMT

Hi Sami,

Thanks for inquiring us and it is very interesting to learn about this issue you encountered. I barely tested with NB-IoT before and need to contract with our modem development team for further analysis, so I need your help to provide more evidence for the next step.

Could you do experiments with AT commands(using nRF9160: Serial LTE modem) and enable modem trace(need to run "AT%xmodemtrace=1,2" to active predefined trace set manually) to get modem trace recordings? According to your feedback, we need the following mode trace recordings:

1) the previous connection has been in LTE-M-mode and changing to NB-IoT-only SIM for a new connection. Expect to see if the scan and join has been established, the modem can randomly drop out from the network in NB-IoT-mode and scan only in LTE-M-mode for several hours or days, while set to %XSYSTEMMODE=1,1,0,0.

2) similar experiment with preferred mode enabled.

Feel free to add more if you have other observations.

Best regards,

Charlie