UC20 fails with "+CME ERROR: no network service" after SIM card removal

Hi all,

Posting first time here, hopefully there is someone who knows UC20 a lot better than me.

We want to use UC20 as network scanner, but after SIM card removal,
When we send AT+COPS=? response is: +CME ERROR: no network service

SIM card was from ATT.
Firmware version is : UC20GQAR03A04M1024
Is there any way to reset BB to default settings, remove ATT config etc. ?

Any lead in this investigation would be much appreciated.

I have to inform you that UC20 is EOL. Are you testing it on your new project? If new project, you can test UC200T instead of UC20.
For restoring the module, AT&F0 is to set all Current Parameters to Manufacturer Defaults. In this case, We suggest that checking if there is 3G netwokr signal.

Many thanks for quick reply.
Old sensors from 2014 (according to BB firmware).
I am looking forward to get rid of them, but customer loves them.
I will update you on success of AT&F0.
We are going to try it right away.

Unfortunately, it did not solve the issue. We can see that AT&F0 defaults stuff by error reporting.
More details from testing:
AT+COPS=0 returns: +CME ERROR: SIM failure
AT+COPS=? returns: +CME ERROR: no network service
AT+QPINC? returns: +CME ERROR: SIM not inserted

Our current working theory is that SIM inserting somehow affects Baseband, so that BB stores some SIM information somewhere, and tries to use this info later causing the problem we have.
Namely modem do not want to scan the area.
3 out of 6 modems only camp on single cell.
1 out of 6 did the scan, but very limited.
2 out of 6 neither camp nor scan.

Unfortunately we do not have option to add SIM card to sensor, neither we have option to add other sensors without history of SIM card insertion.
Neither we can flash the firmware.

Our only option is some esoteric AT command that will delete BB configuration related to “smart” channels or something similar that can cause this issue.

Thanks for contacting Quectel. Since your question is specific to your own situation, the solution might not be referential for other customers, we’d move our discussion off this forum.

Kindly share following details to our support email box(support@quectel.com), we will align local FAE to support you further.

  • Company name / Phone Number:
  • R&D location:
  • Project name (so we can refer to it in the future):
  • Application type:
  • Estimated Annual Units (for series production):
  • Project timeline:
  • Current status:
  • From which distributor do you buy Quectel modules & EVB kits?
  • Do you have EVB kit for this application?
  • Problem description: