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AT command reference

Catalogue + response decoder for the commands SEs see in the wild.

Decode a response line

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[3gpp]

  • AT+CEDRXS Extended Discontinuous Reception (eDRX) configuration. Less aggressive than PSM — modem stays attached but reduces paging frequency.
  • AT+CEER Extended error report. Run this after any unexpected ERROR / +CME ERROR to get the cause code.
  • AT+CEREG EPS / LTE network registration status. The most important triage command on any LTE-M / Cat-1 ticket.
  • AT+CESQ Extended signal quality. The standard way to read RSRP/RSRQ on LTE-M and NB-IoT modems that don't support vendor-specific commands like +QCSQ.
  • AT+CFUN Modem functionality level — controls radio on/off and reset.
  • AT+CGACT Activate or deactivate a PDP context (i.e. bring up the data session).
  • AT+CGATT Attach to / detach from packet-switched service.
  • AT+CGDCONT Define or query PDP contexts (APN configuration). For Hologram SIMs the APN must be exactly 'hologram'.
  • AT+CGPADDR Read the IP address allocated to a PDP context. Useful to confirm context activation actually got an IP.
  • AT+CGREG GPRS / packet-switched (2G/3G data) registration. On LTE-only deployments, expect 0,0 here even when CEREG is healthy.
  • AT+COPS Operator selection. Read current operator, scan available operators, or manually select a network.
  • AT+CPIN Query or enter SIM PIN. The first thing to check on any 'won't connect' ticket.
  • AT+CPSMS Power Saving Mode configuration. Putting the modem to sleep between paging windows for battery savings.
  • AT+CREG Circuit-switched (legacy 2G/3G voice/SMS) registration. Less relevant on Cat-M / NB-IoT deployments.
  • AT+CSCON Signaling connection status indication. Reports whether the modem is in RRC IDLE or RRC CONNECTED.
  • AT+CSQ Signal quality (RSSI). Legacy command, kept for compatibility — for LTE/Cat-M prefer +CESQ or +QCSQ.

[nordic]

  • AT%XSNRSQ Nordic SNR / signal strength readout.
  • AT%XSYSTEMMODE Nordic nRF9160 system mode. Pick LTE-M, NB-IoT, GNSS, and preference between LTE modes.

[quectel]

  • AT+QCFG Modem configuration umbrella command. Many subcommands — band mask, RAT mode, network scan order, etc.
  • AT+QCSQ Quectel-specific signal quality with full RSRP/RSRQ/SINR breakdown plus the active RAT.
  • AT+QENG Engineering / serving-cell info. Cell ID, PCI, EARFCN, signal — the deep RF view.
  • AT+QESIM Manage embedded UICC profiles on Hologram Hyper SIMs (and other eUICC SIMs supported by Quectel modules).
  • AT+QIDNSCFG Configure DNS servers per PDP context. Override carrier-assigned DNS when needed (e.g. carrier DNS is blocked).
  • AT+QIOPEN Open a TCP/UDP socket to a remote host. Quectel's connection-oriented socket primitive.
  • AT+QPING Quectel-built-in ICMP ping. Useful for confirming data path without involving an external host.

[sierra]

  • AT+KSRAT Sierra Wireless RAT-mode selection on HL-series modules.

[simcom]

  • AT+CMNB SIMCom RAT-mode lock. Picks Cat-M, NB-IoT, or both.
  • AT+CSERVINFO SIMCom serving cell information. Equivalent to Quectel +QENG="servingcell".

[telit]

  • AT#SD Telit socket dial — open a TCP connection. Equivalent to Quectel +QIOPEN with TCP.
  • AT#SGACT Telit-specific PDP context activation that returns the IP. Equivalent of +CGACT=1,1 followed by +CGPADDR.

[ublox]

  • AT+UBANDMASK u-blox band mask configuration. Reads/sets the bitmask of LTE bands the modem will scan.
  • AT+UCGED u-blox cell environment description. Detailed RF measurements (RSRP, RSRQ, EARFCN, etc).
  • AT+UPING u-blox ICMP ping.
  • AT+URAT u-blox RAT selection. Picks LTE-M, NB-IoT, GSM, or a preference order across them.