Why no LTE registration denied indicator output after reject by MME

[zwang@2020]

Test Purpose

Verify LTE registration denied indicator.

Pre-conditions

A suitable cell with "h.iijmobile.biz" APN.
LTE URC report enabled.

Environment

• A  nRF9160 FW version: 1.2.0
• B  
• C

Reproduce steps 

Step1. Configure the PDP context with invalid APN,e.g., AT+CGDCONT=0,"IP","h.iijmobile.bizxxxx"\r\n.
Step2. Start LTE service and wait DUT attach the cell.

Expected results / 预期结果

1. DUT output LTE indicator: +MLTEINF:3 after attach reject by MME.

Detail description / 详细描述

1.  No Registration denied indicator output after attach reject.

Related logs / 相关日志

[2020-04-26 17:11:03.690 T]AT+CGDCONT=0,"IP","h.iijmobile.biz3"

[2020-04-26 17:11:03.720 R]OK

[2020-04-26 17:11:11.340 T]AT%XBANDLOCK=2,"10000000"

[2020-04-26 17:11:11.373 R]OK

[2020-04-26 17:11:13.943 T]AT+MLTE=1,1   //Our modem custom command, start LTE service and enable LTE urc.

[2020-04-26 17:11:14.000 R]OK

[2020-04-26 17:11:18.571 R]+MLTEINFI:2,"0001","01A2D101",7,0,0,"11100000","11100000"   

[2020-04-26 17:11:19.579 R]+MLTEINFI:2,"0001","01A2D101",7,0,19,"11100000","11100000"  // The indicator is same as CEREG unsolicited message.

[2020-04-26 17:17:52.661 T]AT+MLTEINF

[2020-04-26 17:17:52.690 R]+MLTEINF:2
OK

[Håkon Alseth]

Hi,

 

Are CMEE error codes enabled?

see here for how to enable it: https://infocenter.nordicsemi.com/topic/ref_at_commands/REF/at_commands/mobile_termination_errors/cnec_set.html?cp=2_1_7_1_0

 

Kind regards,

Håkon

[zwang@2020]

Dear Håkon,

Thank you for your reminding，but my concern is I couldn't trigger Registration denied indicator(The <reg_status> is expected 3) , do you have any suggestions?

[Håkon Alseth]

Hi,

  

+MLTEINFI:2

This is the <stat> field?

It looks like it went back to searching again. Could you try this with at_client and see what it shows?

 

Kind regards,

Håkon

[zwang@2020]

Hi Håkon，

Logs as below:

```

[2020-06-24 10:51:34.699 T]AT+MREBOOT

[2020-06-24 10:51:34.725 R]OK

[2020-06-24 10:51:35.642 R]Ready

[2020-06-24 10:51:39.400 T]AT+MLTE=1,1

[2020-06-24 10:51:39.460 R]OK

[2020-06-24 10:51:40.664 R]+MLTEINFI:2,"0001","01A2D001",7,0,0,"11100000","11100000"

[2020-06-24 10:51:41.192 R]+MLTEINFI:2,"0001","01A2D001",7,0,19,"11100000","11100000"

[2020-06-24 10:51:53.565 T]AT%XMONITOR

[2020-06-24 10:51:53.595 R]%XMONITOR: 2
OK

[2020-06-24 10:51:56.397 T]AT+CEREG?

[2020-06-24 10:51:56.423 R]+CEREG: 5,2,"0001","01A2D001",7,0,19,"11100000","11100000"
OK

```

When the issue happens, <reg_status> checked by Nordic command is also 2 other than 3.

Could you give some suggestions on why it is still 2(searching) when registered rejected by MME?

How to trigger <reg_status>=3?

[Håkon Alseth]

Hi,

 

Could you try this with at_client and see what it prints? I believe it might go to searching again after its rejected, but since you do not have any notification prints, its hard to tell.

 

Kind regards,

Håkon

[zwang@2020]

Hi Håkon,

Sorry,what do you mean at_client? In my understanding, my modem is an at_client.

[zwang@2020]

I'm unable to supply at_client logs now, let's just close this topic.