Problem with function modem_info_params_get() in TN/NTN usecase

Hello,

I am getting an error with the modem_info_params_get() function when I try to get the modem parameters. I am currently using SDK 3.2.0 with the FW MFW_nRF9151-NTN_v1.0.0-1.prealpha modem. In the code, I have TN and NTN configured where the PDN has been configured as follows:

uint8_t cid_tn = 10, cid_ntn = 0;

err = lte_lc_pdn_ctx_configure(cid_tn, "APN", LTE_LC_PDN_FAM_IPV4, NULL);
if (err) {
    LOG_ERR("Error to configure CID_TN: %d", err);
    return err;
}

err = lte_lc_pdn_ctx_configure(cid_ntn, "APN", LTE_LC_PDN_FAM_IPV4, NULL);
if (err) {
    LOG_ERR("Error to configure CID_NTN: %d", err);
    return err;
}

The error message is as follows:

[00:00:07.766,845] <err> modem_info_params: Link data not obtained: 21 -134
[00:00:07.766,845] <err> main: Error -134, modem_info_params_get

The value 21 corresponds to MODEM_INFO_APN (access point name) from the modem_info enum. I used this function on TN-only devices and had no problems. Is this function not yet supported in cases where the device has two APNs (one for TN and one for NTN)?

Regards,
GoncaloS

Parents

0 Øyvind 3 months ago

Hi GoncaloS, could you please provide a modem trace and full application log of your issue? What application are you running on your side? Do you have a nRF9151 SMA DK do test with? Have you followed the steps provided in Evalute NTN on nRF9151 SMA DK product page?

As the instructed in the latter link, please test with the provided application.

Kind regards,
Øyvind
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0 GoncaloS 2 months ago in reply to Øyvind

Hi Øyvind ,

Sorry for the delayed response, but I needed to run some additional tests to verify whether the issue would occur again.
I performed further testing, and the error does not appear consistently. Below are some logs from my application:

// Error -134, modem_info_params_get() with LTE
[23:50:28.978,240] [1;33m<wrn> main: --ST_CONNECT--[0m
[23:50:28.998,565] [0m<inf> main: Vbat: 100% (5.2 V)[0m
[23:50:28.999,450] [0m<inf> main: MODE_OFFLINE set[0m
[23:50:29.000,579] [0m<inf> main: SYSTEM_MODE_LTEM_GPS set[0m
[23:50:29.000,579] [0m<inf> main: Connecting to LTE network...[0m
[23:50:29.041,961] [0m<inf> main: MODE_NORMAL set[0m
[23:50:30.377,868] [0m<inf> main: UE is currently trying to attach or searching ...[0m
[23:50:34.725,128] [0m<inf> main: PDN connection activated[0m
[23:50:34.826,080] [0m<inf> main: Registered, roaming[0m
[23:50:34.826,385] [0m<inf> main: LTE_LC_MODEM_EVT_SEARCH_DONE[0m
[23:50:34.826,538] [0m<inf> main: Connected to LTE network[0m
[23:50:34.826,568] [0m<inf> main: Time to connect: 5.8 s[0m
[23:50:34.836,944] [1;31m<err> modem_info_params: Link data not obtained: 21 -134[0m
[23:50:34.836,944] [1;31m<err> main: Error -134, modem_info_params_get[0m

[23:50:34.837,097] [1;33m<wrn> main: --ST_SEND_DATA--[0m
[23:50:34.837,127] [0m<inf> main: Create the socket[0m
[23:50:34.837,738] [0m<inf> main: Connect the socket to the server[0m

[23:50:34.838,043] [0m<inf> main: [SEND DATA - INTERNAL DATA][0m
[23:50:34.838,104] [0m<inf> main: Total Size (buffer2send): 247 bytes[0m
[23:50:34.838,104] [0m<inf> main: Sending data...[0m
[23:50:34.839,385] [0m<inf> main: Sent 247 bytes[0m
[23:50:35.936,828] [0m<inf> main: Received 21 bytes[0m
[23:50:35.936,920] [0m<inf> main: Time to send+recv pck: 1.098 s[0m
[23:50:35.936,950] [0m<inf> main: Sent all data[0m
[23:50:36.345,977] [0m<inf> main: MODE_OFFLINE set[0m



// Without error with LTE
[22:39:30.886,291] [1;33m<wrn> main: --ST_CONNECT--[0m
[22:39:30.906,616] [0m<inf> main: Vbat: 100% (5.2 V)[0m
[22:39:30.907,501] [0m<inf> main: MODE_OFFLINE set[0m
[22:39:30.908,630] [0m<inf> main: SYSTEM_MODE_LTEM_GPS set[0m
[22:39:30.908,630] [0m<inf> main: Connecting to LTE network...[0m
[22:39:30.949,981] [0m<inf> main: MODE_NORMAL set[0m
[22:39:32.284,179] [0m<inf> main: UE is currently trying to attach or searching ...[0m
[22:39:36.019,439] [0m<inf> main: PDN connection activated[0m
[22:39:36.120,391] [0m<inf> main: Registered, roaming[0m
[22:39:36.120,666] [0m<inf> main: LTE_LC_MODEM_EVT_SEARCH_DONE[0m
[22:39:36.120,849] [0m<inf> main: Connected to LTE network[0m
[22:39:36.120,880] [0m<inf> main: Time to connect: 5.2 s[0m
[22:39:36.159,729] [0m<inf> main: IP: 10.137.22.228; RSRP: -120dBm; Cell ID: 580621; TAC: 48720; Op: 26806; TimeDate: 26/03/01,09:43:05+00[0m
[22:39:36.159,759] [0m<inf> main: Band: 20; Supported bands: (8,20)[0m

[22:39:36.160,186] [1;33m<wrn> main: --ST_SEND_DATA--[0m
[22:39:36.160,217] [0m<inf> main: Create the socket[0m
[22:39:36.160,644] [0m<inf> main: Connect the socket to the server[0m

[22:39:36.160,980] [0m<inf> main: [SEND DATA - INTERNAL DATA][0m
[22:39:36.161,041] [0m<inf> main: Total Size (buffer2send): 215 bytes[0m
[22:39:36.161,041] [0m<inf> main: Sending data...[0m
[22:39:36.162,200] [0m<inf> main: Sent 215 bytes[0m
[22:39:37.140,319] [0m<inf> main: Received 21 bytes[0m
[22:39:37.140,411] [0m<inf> main: Time to send+recv pck: 0.979 s[0m
[22:39:37.140,472] [0m<inf> main: Sent all data[0m
[22:39:37.491,485] [0m<inf> main: MODE_OFFLINE set[0m

In this application, data transmission to the server occurs mostly over LTE, but occasionally some data is sent via NTN. From time to time, some NTN errors also occur, and I am not sure whether they might be related to the error in the modem_info_params function. Based on the analysis of my logs, the error in the modem_info_params() function occurs only when using LTE. Below are the errors I am encountering with NTN:

16:05:14.920 [02:26:36.997,619] [0m<inf> main: %XMONITOR: 2
16:05:14.922 OK
16:05:14.926 [0m
16:05:14.926 [02:26:36.998,321] [0m<inf> main: +CEREG: 5,2,"0FB4","001E9434",14
16:05:14.931 OK
16:05:14.931 [0m
16:05:16.926 [02:26:39.007,904] [0m<inf> main: %SQP: -124,-9,4,-115
16:05:16.928 OK
16:05:16.932 [0m
16:05:16.932 [02:26:39.008,789] [0m<inf> main: %XMONITOR: 2
16:05:16.934 OK
16:05:16.935 [0m
16:05:16.935 [02:26:39.009,490] [0m<inf> main: +CEREG: 5,2,"0FB4","001E9434",14
16:05:16.941 OK
16:05:16.942 [0m
16:05:18.936 [02:26:41.019,073] [0m<inf> main: %SQP: -123,-8,4,-115
16:05:18.942 OK
16:05:18.942 [0m
16:05:18.943 [02:26:41.019,958] [0m<inf> main: %XMONITOR: 2
16:05:18.947 OK
16:05:18.947 [0m
16:05:18.947 [02:26:41.020,660] [0m<inf> main: +CEREG: 5,2,"0FB4","001E9434",14
16:05:18.955 OK
16:05:18.955 [0m
16:05:18.957 [02:26:42.023,773] [1;31m<err> main: ESM Error - Code: 38[0m
16:05:18.962 [02:26:42.024,078] [1;33m<wrn> lte_lc: Registration rejected, EMM cause: 19, Cell ID: 2004020, Tracking area: 4020, LTE mode: 14[0m
16:05:42.178 [02:27:05.135,040] [0m<inf> main: Timeout - connecting NTN[0m
16:05:42.184 [02:27:05.135,101] [0m<inf> main: Time to try connect: 120.4 s[0m

Below is modem_info_get() and modem_data_get() functions:

void modem_info_get(void){
    int err = modem_info_params_get(&modem_param);
	if(err != 0){
		LOG_ERR("Error %d, modem_info_params_get", err);
	}
	else{
		LOG_INF("IP: %s; RSRP: %ddBm; Cell ID: %d; TAC: %d; Op: %s; TimeDate: %s", modem_param.network.ip_address.value_string, 
			RSRP_IDX_TO_DBM(modem_param.network.rsrp.value), (uint32_t)modem_param.network.cellid_dec, modem_param.network.area_code.value, 
			modem_param.network.current_operator.value_string, modem_param.network.date_time.value_string); 
		LOG_INF("Band: %d; Supported bands: %s", modem_param.network.current_band.value, modem_param.network.sup_band.value_string);
	}
}

static int modem_data_get(struct lte_param *param)
{
	enum modem_info_data_type data_type;
	int ret;

	data_type = modem_info_data_type_get(param->type);

	if (data_type == MODEM_INFO_DATA_TYPE_INVALID) {
		return -EINVAL;
	}

	if (data_type == MODEM_INFO_DATA_TYPE_STRING) {
		ret = modem_info_string_get(param->type,
				param->value_string,
				sizeof(param->value_string));
		if (ret < 0) {
			LOG_ERR("Link data not obtained: %d %d", param->type, ret);
			return ret;
		}
	} else if (data_type == MODEM_INFO_DATA_TYPE_NUM_INT) {
		ret = modem_info_short_get(param->type, &param->value);
		if (ret < 0) {
			LOG_ERR("Link data not obtained: %d", ret);
			return ret;
		}
	}

	return 0;
}

Could you please help me understand what might be causing this issue?

Best regards,
GoncaloS

0 Håkon Alseth 2 months ago in reply to GoncaloS
Hi GoncaloS,

My apologies for the late reply.

The error:

modem_info_params: Link data not obtained: 21 -134

is emitted when the context is not up.

The second log shows ESM/EMM cause codes:

16:05:18.957 [02:26:42.023,773] [1;31m<err> main: ESM Error - Code: 38[0m 16:05:18.962 [02:26:42.024,078] [1;33m<wrn> lte_lc: Registration rejected, EMM cause: 19, Cell ID: 2004020, Tracking area: 4020, LTE mode: 14[0m

Have you followed the getting started, as Øyvind pointed towards?

Kind regards,

Håkon
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0 GoncaloS 2 months ago in reply to Håkon Alseth

Hello Håkon Alseth ,

Yes, I tried to follow the guide available NTN guide and only used the available functions for the NTN configuration instead AT commands. The configurations I did at the start of the code are included in my last reply. After that, I only connected to LTE and NTN using the commands i Had already sent. Both errors occur randomly, but most of the time it works without problems. Could these errors be caused by a bug in the PDN configuration for more than one profile ?

Regards,
GoncaloS
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0 Håkon Alseth 1 month ago in reply to GoncaloS

Hi GoncaloS,

Which SIM card / telecom vendor are you using for connection towards GEO/LEO?

As mentioned, it seems that the NTN network you're connecting to, or have coverage for in your area, is rejecting your attach.

Kind regards,

Håkon
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0 GoncaloS 1 month ago in reply to Håkon Alseth

Hi Håkon Alseth ,

I am using a Monogoto SIM Card. On the Monogoto management page, I can see the following:

// Failed Connection
28-Feb-2026 16:43:00 | Event=HSS_ULR | Operator=Skylo NTN Technologies | MME=core02.prod-eu.epc.mnc098.mcc901.3gppnetwork.org
28-Feb-2026 16:43:00 | Event=HSS_ULA | Result=SUCCESS | Operator=Skylo NTN Technologies 

// Successful connection
28-Feb-2026 13:47:11 | Event=HSS_ULR | Operator=Skylo NTN Technologies | MME=core02.prod-eu.epc.mnc098.mcc901.3gppnetwork.org
28-Feb-2026 13:47:11 | Event=HSS_ULA | Result=SUCCESS | Operator=Skylo NTN Technologies 
28-Feb-2026 13:47:16 | Event=GGSN_AUTHENTICATE_PDP_CONTENT | Operator=Skylo NTN Technologies | Action=authenticate_pdp_context v2 | SGSN=10.99.5.199 | RAI=null | AllowedBytes=20971520
28-Feb-2026 13:47:16 | Event=GGSN_AUTHENTICATE_PDP_CONTENT_RESULT | Result=SUCCESS | Operator=Skylo NTN Technologies | SessionID=1223969419 | AllowedBytes=20971520 | IP=10.137.22.230
28-Feb-2026 13:48:12 | Event=DATA | Operator=Skylo NTN Technologies | SessionID=2.40076E+14 | Usage=412 bytes
28-Feb-2026 13:48:12 | Event=GGSN_DELETE_PDP_CONTENT | Operator=Skylo NTN Technologies | Action=delete_pdp_context | SessionID=1223969419 | Upload=314 | Download=98 | Total=412 | IP=10.137.22.230 | InitialTime=28/02/2026 13:47 | Cause=User Request

I talked with them, and they said that on their side, there is no limitations on the NTN network.

Regards,
GoncaloS

0 Håkon Alseth 1 month ago in reply to GoncaloS
Hi GoncaloS,

I checked with R&D, and confirmed that the ESM/EMM cause codes that you are seeing is very similar in NTN as they are in "normal" LTE-M or NB-IoT mode.

The cause code of 38 indicates:

Cause #38 – Network failure This ESM cause is used by the network to indicate that the requested service was rejected due to an error situation in the network.

The UE in this case is only the messenger, and cannot actively tell anything else than to relay the ESM/EMM cause code it receives from the network. If this is a situation that occurs often, please let the network provider know about this.

Kind regards,

Håkon
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0 Håkon Alseth 1 month ago in reply to GoncaloS
Hi GoncaloS,

I checked with R&D, and confirmed that the ESM/EMM cause codes that you are seeing is very similar in NTN as they are in "normal" LTE-M or NB-IoT mode.

The cause code of 38 indicates:

Cause #38 – Network failure This ESM cause is used by the network to indicate that the requested service was rejected due to an error situation in the network.

The UE in this case is only the messenger, and cannot actively tell anything else than to relay the ESM/EMM cause code it receives from the network. If this is a situation that occurs often, please let the network provider know about this.

Kind regards,

Håkon
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0 GoncaloS 1 month ago in reply to Håkon Alseth

Hi Håkon Alseth ,

So, what can we do when these errors appear? What about the error "modem_info_params: Link data not obtained: 21 -134" ?

Regards,
GoncaloS
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0 Håkon Alseth 1 month ago in reply to GoncaloS

Hi,

GoncaloS said:
What about the error "modem_info_params: Link data not obtained: 21 -134" ?

This is due to the APN not being connected or obtained at the time of parsing.

This could be due to the response time of the APN itself, or that the link quality is weak (low signal strength) - one of your logs shows a RSRP of -120 dBm, which is very low.

Kind regards,

Håkon
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