Send a SMS without PDN configured

[GoncaloS]

Hi, 

I have a question about the SMS sample (https://docs.nordicsemi.com/bundle/ncs-2.6.1/page/nrf/samples/cellular/sms/README.html). I can use this sample to send and receive SMS, but when I configured the PDN with the different APN, the sample cannot send or receive SMS. Is it possible to send SMS without PDN configured? 

I think the function used in this sample to connect to LTE network (lte_lc_connect()), connects to LTE network with PDN already configured. If so, is it possible to send SMS without PDN configured?

Regards, 

GoncaloS

[Øyvind]

Hello, 

Are you able to share some more details on this issue? Do you get an error when trying to send with PDN? Are the PDN settings needed by the network/SIM? 

What modem FW are you running on you device? I assume that you are running nRF Connect SDK v2.6.1?

Kind regards,
Øyvind

[GoncaloS]

Hi,

In theory, you don't need an active data connection to send SMS, you just need the device to be connected to an LTE network. In the SMS example provided by Nordic, the device connects to an LTE network using the lte_lc_connect() function and then the modem is able to send and receive messages if the apn is previously configured. If you change to a different apn than the one supported (using the pdn_ctx_configure function), the example of sending messages no longer works. So it seems that the example using the lte_lc_connect function connects to an LTE network with an active data connection, whereas for SMS you don't need an active data connection, you just need to be connected to an LTE network. Another question is, when we use the lte_lc_connect function, does the device connect to an LTE network with an active data connection or not?

I am using Modem FW 2.0.1 and the nRF Connect SDK v2.6.1.

Regards,

GoncaloS

[Øyvind]

Hello, 

From the logs I can see that your device receives reject cause 19 in the CEREG response. 

Cause #19 – ESM failure
This EMM cause is sent to the UE when there is a failure in the ESM message contained in the EMM message.

This means we do need a modem trace from your device. 

GoncaloS said:

Error when creating trace: unable to locate db directory plugin path: C:\Users\xxx\.nrfconnect-apps\node_modules\pc-nrfconnect-cellularmonitor\node_modules\@nordicsemiconductor\nrf-monitor-lib-js\Release\win32-x64\nrfml-insight-source.nrfml

Could you please provide more information about this, e.g. screenshot of your Cellular Monitor?

[GoncaloS]

Hello, 

Sure, I'll send you two pictures.

Regards,
GoncaloS

[Øyvind]

Hello, thanks for your patience with this 

When trying to start a modem trace, can you please try selecting mfw 2.0.1 manually from the modem trace database list

Kind regards,
Øyvind

[GoncaloS]

Hello, 

Modem trace with SMS sample working:

trace-2024-11-05T15-37-33.314Z.mtrace
Modem trace with SMS sample that not works:

trace-2024-11-05T15-41-15.049Z.mtrace

I still have another question: when we use the lte_lc_connect function, does the device connect to an LTE network with an active data connection or not?

Regards,
GoncaloS

[Øyvind]

Hello, 

What PDN/APN are you trying to connect? There seems to be an issue with this connection i.e. LTE attach fails. Possible reason is invalid APN. nRF91 does not support LTE attach without a data connection, so the APN must be valid.

Kind regards,
Øyvind