nrf9160 will not register with cellular network

[Eric S.]

I started an evaluation using the nrf9160 DK development board in June, 2020. The project was put on hold but it has now restarted. In June 2020 I was able to successfully connect with the nrf cloud and communicate over the cellular LTE-M network. Upon restarting this project I cannot get the nrf9160 to register with a cellular network. Using the LTE Link Monitor I can see the board successfully boot up and attempt to connect to a cellular network and I can see LED3 blinking as the board is searching for an LTE connection. However, the board never connects and LED4 never comes on and the LTE Link monitor shows a cellular connection timeout and the board goes into an idle state. I am in Tucson, Arizona, USA with good cell coverage from the major cell carriers.

Following is what I have done to update and try to achieve a connection:

1. I updated all of my NRF CONNECT software applications to latest versions. Specifically the nrf Connect programmer is at version v1.4.11. The LTE Link Monitor is at version v1.1.10

2. Using the nrf Connect programmer, I updated the nrf9160 asset tracking and modem software.

      Asset tracking firmware img_app_bl>nrf9160dk_asset_tracker_ltem_2021-03-01_8e8c6089.hex.

     I also tried  img_app_bl>external_gps_antenna>nrf9160dk_asset_tracker_ltem_ext_gps_2021-03-01_8e8c6089.hex. 

     I updated the modem software with mfwnrf9160123.zip.

3. I logged into my nrf Cloud account and purchased an additional 20 Meg of data for the iBasis SIM that came with the nrf9160 dk development board since I was concerned that the sim may have expired since I had not used it for almost 1 year.

4. I reset my device in the nrf Cloud since I was going to update the certificate because I was not sure if the software updates would affect the previously installed certificate.

5. I generated a new certificate in the nrf Cloud and downloaded the file to my computer. Double checked the IMEI and HWID numbers.

6. I removed the iBasis sim, launched the LTE Link monitor, powered up the board and opened the serial port to the board.

7. Performed the AT+CFUN? AT+CFUN=4, AT+CFUN? commands to verify that the modem was offline.(AT+CFUN response 4)

8. Clicked on the Certificate Manager button, dragged and dropped the downloaded certificate file, confirmed that the security tag is 16842753, confirmed that automatic requests was not checked, and successfully installed the updated Certificate from what the log reported. 

9. I turned off the board and re-installed the iBasis sim and powered the board back on.

10. Launched the LTE Link monitor, connected to the nrf9160 dk board.

11. Pressed the board reset button and watched the LTE Link monitor and blinking LED3 and waited with no connection results. LED4 never came on after 10 minutes.

12. I could see in the monitor that the board booted up and saw the message connecting to LTE network.

13.Sample of log file:

2021-06-11T20:37:43.647Z DEBUG modem << [00:00:00.225,189] [0m<inf> watchdog: Watchdog feed enabled. Timeout: 30000[0m
2021-06-11T20:37:43.716Z DEBUG modem << [00:00:00.239,593] [0m<dbg> nrf_cloud_transport.nct_client_id_get: client_id = nrf-352656100380339[0m
2021-06-11T20:37:43.719Z DEBUG modem << [00:00:00.248,779] [0m<dbg> nrf_cloud_transport.nct_topics_populate: shadow_base_topic: $aws/things/nrf-352656100380339/shadow[0m
2021-06-11T20:37:43.721Z DEBUG modem << [00:00:00.260,406] [0m<dbg> nrf_cloud_transport.nct_topics_populate: accepted_topic: nrf-352656100380339/shadow/get/accepted[0m
2021-06-11T20:37:43.723Z DEBUG modem << [00:00:00.271,881] [0m<dbg> nrf_cloud_transport.nct_topics_populate: rejected_topic: $aws/things/nrf-352656100380339/shadow/get/rejected[0m
2021-06-11T20:37:43.725Z DEBUG modem << [00:00:00.284,454] [0m<dbg> nrf_cloud_transport.nct_topics_populate: update_delta_topic: $aws/things/nrf-352656100380339/shadow/update/delta[0m
2021-06-11T20:37:43.748Z DEBUG modem << [00:00:00.297,302] [0m<dbg> nrf_cloud_transport.nct_topics_populate: update_topic: $aws/things/nrf-352656100380339/shadow/update[0m
2021-06-11T20:37:43.751Z DEBUG modem << [00:00:00.309,112] [0m<dbg> nrf_cloud_transport.nct_topics_populate: shadow_get_topic: $aws/things/nrf-352656100380339/shadow/get[0m
2021-06-11T20:37:43.754Z DEBUG modem << [00:00:00.321,044] [0m<inf> asset_tracker: Connecting to LTE network.[0m
2021-06-11T20:37:43.758Z DEBUG modem << [00:00:00.327,667] [0m<inf> asset_tracker: This may take several minutes.[0m
2021-06-11T20:38:45.406Z DEBUG modem << +CEREG: 2,"345B","0150A417",7,0,0,"11100000","11100000"
2021-06-11T20:38:45.441Z DEBUG modem << [00:01:01.993,927] [0m<inf> asset_tracker: LTE cell changed: Cell ID: 22062103, Tracking area: 13403[0m
2021-06-11T20:38:45.476Z DEBUG modem << +CSCON: 1
2021-06-11T20:38:45.479Z DEBUG modem << [00:01:02.055,755] [0m<inf> asset_tracker: RRC mode: Connected[0m
2021-06-11T20:38:45.535Z DEBUG modem << +CEREG: 2,"345B","0150A417",7,0,11,"11100000","11100000"
2021-06-11T20:38:46.827Z DEBUG modem << +CSCON: 0
2021-06-11T20:38:46.834Z DEBUG modem << [00:01:03.416,900] [0m<inf> asset_tracker: RRC mode: Idle[0m
2021-06-11T20:38:47.164Z DEBUG modem << +CEREG: 2,"170C","0059E401",7,0,11,"11100000","11100000"
2021-06-11T20:38:47.186Z DEBUG modem << [00:01:03.754,089] [0m<inf> asset_tracker: LTE cell changed: Cell ID: 5891073, Tracking area: 5900[0m
2021-06-11T20:38:47.214Z DEBUG modem << +CSCON: 1
2021-06-11T20:38:47.219Z DEBUG modem << [00:01:03.801,849] [0m<inf> asset_tracker: RRC mode: Connected[0m
2021-06-11T20:38:48.976Z DEBUG modem << +CEREG: 4,"170C","0059E401",7,0,15,"11100000","11100000"
2021-06-11T20:38:50.223Z DEBUG modem << +CSCON: 0
2021-06-11T20:38:50.234Z DEBUG modem << [00:01:06.810,974] [0m<inf> asset_tracker: RRC mode: Idle[0m
2021-06-11T20:38:50.249Z DEBUG modem << +CEREG: 4,"FFFE","FFFFFFFF",7,0,15,"11100000","11100000"
2021-06-11T20:38:50.269Z DEBUG modem << [00:01:06.830,291] [0m<inf> asset_tracker: LTE cell changed: Cell ID: -1, Tracking area: 65534[0m
2021-06-11T20:38:51.804Z DEBUG modem << +CEREG: 2,"345B","0150A417",7,0,15,"11100000","11100000"
2021-06-11T20:38:51.828Z DEBUG modem << [00:01:08.394,042] [0m<inf> asset_tracker: LTE cell changed: Cell ID: 22062103, Tracking area: 13403[0m
2021-06-11T20:38:51.868Z DEBUG modem << +CSCON: 1
2021-06-11T20:38:51.882Z DEBUG modem << [00:01:08.455,780] [0m<inf> asset_tracker: RRC mode: Connected[0m
2021-06-11T20:38:53.489Z DEBUG modem << +CEREG: 4,"345B","0150A417",7,0,15,"11100000","11100000"
2021-06-11T20:38:54.827Z DEBUG modem << +CSCON: 0
2021-06-11T20:38:54.839Z DEBUG modem << [00:01:11.416,992] [0m<inf> asset_tracker: RRC mode: Idle[0m
2021-06-11T20:38:54.844Z DEBUG modem << +CEREG: 4,"FFFE","FFFFFFFF",7,0,15,"11100000","11100000"
2021-06-11T20:38:54.866Z DEBUG modem << [00:01:11.434,356] [0m<inf> asset_tracker: LTE cell changed: Cell ID: -1, Tracking area: 65534[0m
2021-06-11T20:38:55.646Z DEBUG modem << +CEREG: 2,"800B","07551811",7,0,15,"11100000","11100000"
2021-06-11T20:38:55.669Z DEBUG modem << [00:01:12.234,039] [0m<inf> asset_tracker: LTE cell changed: Cell ID: 123017233, Tracking area: 32779[0m
2021-06-11T20:38:55.756Z DEBUG modem << +CSCON: 1
2021-06-11T20:38:55.763Z DEBUG modem << [00:01:12.346,282] [0m<inf> asset_tracker: RRC mode: Connected[0m
2021-06-11T20:38:57.121Z DEBUG modem << +CEREG: 4,"800B","07551811",7,0,15,"11100000","11100000"
2021-06-11T20:38:58.429Z DEBUG modem << +CSCON: 0
2021-06-11T20:38:58.443Z DEBUG modem << [00:01:15.017,150] [0m<inf> asset_tracker: RRC mode: Idle[0m
2021-06-11T20:38:58.459Z DEBUG modem << +CEREG: 4,"FFFE","FFFFFFFF",7,0,15,"11100000","11100000"
2021-06-11T20:38:58.468Z DEBUG modem << [00:01:15.034,393] [0m<inf> asset_tracker: LTE cell changed: Cell ID: -1, Tracking area: 65534[0m
2021-06-11T20:38:59.488Z DEBUG modem << +CEREG: 2,"800B","07551811",7,0,15,"11100000","11100000"
2021-06-11T20:38:59.508Z DEBUG modem << [00:01:16.077,056] [0m<inf> asset_tracker: LTE cell changed: Cell ID: 123017233, Tracking area: 32779[0m
2021-06-11T20:38:59.596Z DEBUG modem << +CSCON: 1
2021-06-11T20:38:59.603Z DEBUG modem << [00:01:16.186,309] [0m<inf> asset_tracker: RRC mode: Connected[0m
2021-06-11T20:38:59.686Z DEBUG modem << +CEREG: 2,"800B","07551811",7,0,11,"11100000","11100000"
2021-06-11T20:39:00.987Z DEBUG modem << +CSCON: 0
2021-06-11T20:39:01.001Z DEBUG modem << [00:01:17.577,178] [0m<inf> asset_tracker: RRC mode: Idle[0m
2021-06-11T20:39:01.016Z DEBUG modem << +CEREG: 4,"800B","07551811",7,0,11,"11100000","11100000"
 

14. After about 8 minutes I see in the log a timed out entry

2021-06-11T20:48:24.028Z DEBUG modem << [00:01:17.901,977] [0m<inf> asset_tracker: RRC mode: Idle[0m
2021-06-11T20:48:24.034Z DEBUG modem << +CEREG: 4,"FFFE","FFFFFFFF",7,0,15,"11100000","11100000"
2021-06-11T20:48:24.043Z DEBUG modem << [00:01:17.924,255] [0m<inf> asset_tracker: LTE cell changed: Cell ID: -1, Tracking area: 65534[0m
2021-06-11T20:48:24.303Z DEBUG modem << +CEREG: 4,"170C","0059E401",7,0,15,"11100000","11100000"
2021-06-11T20:48:24.324Z DEBUG modem << [00:01:18.194,580] [0m<inf> asset_tracker: LTE cell changed: Cell ID: 5891073, Tracking area: 5900[0m
2021-06-11T20:57:06.485Z DEBUG modem << [00:10:00.385,040] [0m<inf> lte_lc: Network connection attempt timed out[0m
2021-06-11T20:57:06.526Z DEBUG modem << +CEREG: 0,"170C","0059E401",7,0,15,"11100000","11100000"
2021-06-11T20:57:06.582Z DEBUG modem << [00:10:00.481,903] [0m<inf> lte_lc: Using fallback network mode[0m

I would appreciate any help or direction to resolve this issue

Eric Scheidemantel

[DevinCallahan]

Looking at these events:

2021-06-11T20:38:45.535Z DEBUG modem << +CEREG: 2,"345B","0150A417",7,0,11,"11100000","11100000"

2021-06-11T20:38:48.976Z DEBUG modem << +CEREG: 4,"170C","0059E401",7,0,15,"11100000","11100000"

 

The "7,0,11" part of the CEREG status is likely from "CNEC_EMM error 11" which is "PLMN not allowed", so the PLMN your modem tried to attach to denied it.

The "7,0,15" is likely "CNEC_EMM error 15" which is "No suitable cells in tracking area", which I would guess means the modem hasn't found any other networks to attach to during its scan.

I would say the SIM you are using still doesn't have permission for the network in your area, despite you having purchased more data for it.

I don't have any insight on how to resolve that unfortunately, but hopefully knowing that's the issue helps!

[Eric S.]

I followed up with iBasis and they suggested I try to force connection to either Verizon or ATT which are the carriers that they use for the US LTE-M. I am not sure I did this correctly but I use the AT command interface and tried: AT+CGDCONT=1,"IP","m2m.com.attz" for ATT connection and tried AT+CGDCONT=1,"IP","vzwinternet" to force the APN. Neither worked in establishing a connection to the cell network.

Any advice would be appreciated.

Eric Scheidemantel

[Eric S.]

I decided to get a Hologram sim and I now can connect to LTE-M cellular network so I have confirmed that it is the iBasis sim. However I still cannot connect to the nordic cloud even after I generate new Certificates and install into the nRF916 DK. In Nordic Cloud I did a reset device. I then tried to add a new device using the same IMEI and HWID but I get an error No device found for this id. The device has not yet been provisioned. Troubleshoot nRF Code 40412. What am I doing wrong?

Thanks Eric Scheidemantel