Quectel RG255C series: APN and network setup with an IoT SIM

Updated 27 October 2026

The Quectel RG255C series is a cellular module for 5G RedCap, with LTE Cat-4; it also has GNSS. 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 Quectel's manuals, standard ones from 3GPP TS 27.007; each cites its document.

Key facts

Quectel's specification marks GNSS as optional: it depends on the version ordered.

Source: Quectel, RG255C series product page. Checked 27 October 2026. Quectel's AT manuals carry a confidentiality notice: we cite them by title and page, without linking the files.

Set the APN

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

Source: Quectel RG255C Series&RM255C-GL AT Commands Manual V1.1, page 88.

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

Choose the radio technology

AT+QNWPREFCFG="mode_pref",NR5G

Accepted values: AUTO, LTE and NR5G, combined with a colon (for example LTE:NR5G). The setting is kept after a reboot.

Source: Quectel RG255C Series&RM255C-GL AT Commands Manual V1.1, page 117.

Open the data connection

AT+QMAP="connect",0,1

Starts the data call of rule 0; the APN profile of each rule is set with AT+QMAP="MPDN_rule".

Source: Quectel RG255C Series&RM255C-GL AT Commands Manual V1.1, page 210.

Choose the USB network interface

AT+QCFG="usbnet",2

0 = RmNet, 1 = ECM, 2 = MBIM, 3 = RNDIS. Takes effect after a reboot.

Source: Quectel RG255C Series&RM255C-GL AT Commands Manual V1.1, pages 48 and 49.

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+QENG="servingcell"

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 Quectel RG255C Series&RM255C-GL AT Commands Manual V1.1, page 100.

Networks and shutdowns

• No 2G or 3G dependency: the RG255C series 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.