u-blox SARA-R422: APN and network setup with an IoT SIM

Updated 27 October 2026

The u-blox SARA-R422 is a cellular module for LTE-M and NB-IoT with 2G fallback. With an IoT SIM, you set the APN with AT+CGDCONT=1,"IP","<apn>", choose the radio technology, then check that the module is registered, at home or in roaming. Vendor commands come from u-blox's manuals, standard ones from 3GPP TS 27.007; each cites its document.

Key facts

u-blox describes it as	LTE Cat M1 / NB2 and 2G module
Radio technologies	LTE-M, NB-IoT, 2G
2G fallback	yes
GNSS	no
Form factor	LGA, 96 pins, 26.0 × 16.0 × 2.12 mm
Variants and regions	Multi region; LTE bands 1, 2, 3, 4, 5, 8, 12, 13, 18, 19, 20, 25, 26, 28, 66, 85 and 2G 4-band; 3GPP Release 14 (Cat M1, Cat NB2). SARA-R422M10S integrates a u-blox M10 GNSS receiver.
Power saving	PSM: yes; eDRX: yes

SARA-R42 series: SARA-R422, SARA-R422S and SARA-R422M10S; only the SARA-R422M10S has GNSS.

Source: Trasna, SARA-R42 series product page. Checked 27 October 2026. u-blox sold its cellular modules to Trasna in March 2025: current data sheets and AT manuals are Trasna-branded. We cite them by title and page.

Set the APN

AT+CGDCONT=1,"IP","<apn>"

Context 1 is the initial default EPS bearer and cannot be undefined on the SARA-R422.

Source: u-blox (Trasna) LEXI-R4 / SARA-R4 series AT commands manual R31, pages 194 and 196.

Replace <apn> with the APN shown in your M2M.global account: the internet APN, or your private APN.

Choose the radio technology

AT+URAT=7,8,9

7 = LTE-M, 8 = NB-IoT, 9 = GPRS/eGPRS, in order of preference (the SARA-R422's factory values).

Source: u-blox (Trasna) LEXI-R4 / SARA-R4 series AT commands manual R31, pages 60 and 61.

Check the operator profile

AT+UMNOPROF?

Reads the network operator profile; set it with AT+UMNOPROF=<MNO>, using a value from the manual's list. A profile that does not match the network can prevent registration.

Source: u-blox (Trasna) LEXI-R4 / SARA-R4 series AT commands manual R31, pages 94 and 96.

Open the data connection

AT+CGACT=1,1

Source: u-blox (Trasna) LEXI-R4 / SARA-R4 series AT commands manual R31, page 202.

Check that it works

AT+CPIN?        SIM ready? expect +CPIN: READY
AT+CEREG?       LTE registration: stat 1 = home network, 5 = roaming
AT+COPS?        network the module is using
AT+CGDCONT?     APN actually configured
AT+CESQ

An IoT SIM that works in many countries is often registered in roaming: +CEREG: 0,5 is a valid, working registration. Firmware that waits only for status 1 (home network) never goes online on such a SIM. Status values come from 3GPP TS 27.007; the signal command from u-blox (Trasna) LEXI-R4 / SARA-R4 series AT commands manual R31, page 56.

To save battery, request PSM with AT+CPSMS and eDRX with AT+CEDRXS (3GPP TS 27.007); the network decides which timers it grants.

Networks and shutdowns

LTE-M and NB-IoT run on 4G networks, but not every operator offers them, and roaming on them depends on agreements between operators. Check the coverage by country before you deploy.
2G fallback helps only where 2G still runs. Many operators have switched it off: see the 2G and 3G shutdown dates.
Private delivery works with any module: the privacy is in the network path, not in the device. See private delivery.

The SIM: IoT SIM cards and IoT eSIM. All commands explained: AT commands.

Frequently asked questions

How do I set the APN on the u-blox SARA-R422?

Send AT+CGDCONT=1,"IP","<apn>", with the APN of your SIM in place of <apn>. Source: u-blox (Trasna) LEXI-R4 / SARA-R4 series AT commands manual R31.

Does the u-blox SARA-R422 support LTE-M and NB-IoT?

u-blox states both for the SARA-R422: LTE-M and NB-IoT with 2G fallback.

Does the u-blox SARA-R422 fall back to 2G?

Yes, u-blox lists 2G (GSM/GPRS/EGPRS) fallback for the SARA-R422. It only helps where operators still run 2G.

Why does my SARA-R422 show +CEREG: 0,5?

Status 5 means registered in roaming, a normal working state for an IoT SIM that uses partner networks. Treat it like status 1 (home network) in your firmware.