nRF 91x1 changing APN

[teba99]

Hi,

I am developing an application with LTE-M connectivity to nRF Cloud. Our previous SIM apparently supported auto-APN provisioning, we did not have to set the APN, the code connected fine (using SDK 2.9.0).

Now we are switching to a Vodafone SIM which has a custom APN for us, and apparently this does not auto-provision, so the APN must be set in the device explicitly.

I reviewed the PDN APN documentation and browsed the forums (finding many outdated posts on this topic), but have not yet found a definitive description on what is needed to change the APN.

What I tried so far is (prj.conf)

CONFIG_PDN=y

CONFIG_PDN_ESM_STRERROR=y

CONFIG_PDN_DEFAULTS_OVERRIDE=y

CONFIG_PDN_INIT_PRIORITY=89

CONFIG_PDN_DEFAULT_FAM_IPV4V6=y

CONFIG_PDN_DEFAULT_APN="my-apn"

but I get 

modem_info_params: Link data not obtained: 5 -5

and later

lte_lc: Registration rejected, EMM cause: 19, Cell ID: 32026369, Tracking area: 16543, LTE mode: 7

I can see in the Vodafone portal that the device has registered on LTE-M, but has not established a data session, presumably because it is not using the custom APN.

It is not clear to me if configuration alone is sufficient and the PDN / LTE library will automatically use that configured APN, or whether it is necessary to change the code to explicitly create a new PDN context using pdn_ctx_create() before calling nrf_cloud_connect(). 

Any help is appreciated.

Thanks,

Terrence

[dejans]

Hi Terrence,

Looking at PDN library configuration, it does not seem that you omitted any of required Kconfig options (except for optional authentication ones). 

Can you provide complete error log?

Best regards,
Dejan

[teba99]

Hi dejans 

Thanks for your quick reply.

After much debugging it turns out that some of our VF SIMs require special setup on the backend, which was not yet done for this SIM. So the nRF9151 connected to the network, but then was rejected by VF. After we completed the setup, the SIM connected with the default APN config (no custom APN config needed). 

However, it's good to know that the above mechanism is generally the right way to change the APN, in case we need that in the future.

Thanks,
-- Terrence