u-blox SARA-R510S: APN and network setup with an IoT SIM

Updated 27 October 2026

The u-blox SARA-R510S is a cellular module for LTE-M and NB-IoT. 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-M / NB-IoT module based on the UBX-R5 chipset
Radio technologies	LTE-M, NB-IoT
2G fallback	no
GNSS	not stated
Form factor	LGA, 96 pins, 26.0 × 16.0 × 2.2 mm
Variants and regions	Multi-regional; LTE FDD bands 1, 2, 3, 4, 5, 8, 12, 13, 18, 19, 20, 25, 26, 28, 66, 71, 85 (66, 71, 85 not on "00B"); versions 00B, 01B, 61B, 71B (61B listed for Japan on the archived page).
Power saving	PSM: yes; eDRX: yes

The SARA-R510M8S is the same module with a u-blox M8 GNSS receiver. NB-IoT and eDRX deep sleep are not supported by the "00B" product versions. Check availability with Trasna before a new design.

Source: u-blox, SARA-R5 series page (archived December 2024). 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.

Source: u-blox (Trasna) LEXI-R5 / SARA-R5 series AT commands manual R21, pages 237 and 240.

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

One technology at a time: 7 = LTE-M, 8 = NB-IoT.

Source: u-blox (Trasna) LEXI-R5 / SARA-R5 series AT commands manual R21, pages 69 and 70.

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-R5 / SARA-R5 series AT commands manual R21, page 136.

Open the data connection

AT+UPSDA=0,3

Activates packet data profile 0 of the internal IP stack (action 3 = activate); the profile is configured with AT+UPSD.

Source: u-blox (Trasna) LEXI-R5 / SARA-R5 series AT commands manual R21, pages 245 to 250.

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-R5 / SARA-R5 series AT commands manual R21, page 61.

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.
No 2G or 3G dependency: the SARA-R510S is not affected by 2G and 3G shutdowns.
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-R510S?

Send AT+CGDCONT=1,"IP","<apn>", with the APN of your SIM in place of <apn>. Source: u-blox (Trasna) LEXI-R5 / SARA-R5 series AT commands manual R21.

Does the u-blox SARA-R510S support LTE-M and NB-IoT?

u-blox states both for the SARA-R510S: LTE-M and NB-IoT.

Does the u-blox SARA-R510S fall back to 2G?

No. The SARA-R510S has no 2G fallback, so 2G shutdowns do not affect it.

Why does my SARA-R510S 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.