CREG – request network registration status

Verifies the current network registration status of the module. Set the mode first to control the returned information and automatic status updates.

Test command

Run the command:

AT+CREG=?

The module returns:

+CREG: (0-2)
OK

Read command

Set the mode with the Write command before running:

AT+CREG?

The response depends on the selected mode. The first number is the mode:

+CREG: 0
OK

+CREG: 1
OK

+CREG: 2,[,,[,]]

For mode 2, the response includes:

• The registration status:

  • 0 — Not registered. The device is not searching for an operator.
  • 1 — Registered on the home network.
  • 2 — Not registered, but searching for an operator.
  • 3 — Registration denied.
  • 4 — Unknown, for example, when the device is out of range.
  • 5 — Registered while roaming on a foreign network.
• A two-byte location area code in hexadecimal format.
• A cell ID in hexadecimal format:

  • 16 bit for 2G.
  • 28 bit for 3G or 4G.
• The radio access technology:

  • 0 — GSM.
  • 2 — UTRAN.
  • 3 — GSM with EGPRS.
  • 4 — UTRAN with HSDPA.
  • 5 — UTRAN with HSUPA.
  • 6 — UTRAN with HSDPA and HSUPA.
  • 7 — E-UTRAN.

The module returns ERROR if the command fails.

Write command

Run the command:

AT+CREG=

Set the value to one of the following:

• 0 — Disable unsolicited network registration results. Check the registration status manually.
• 1 — Enable unsolicited network registration results. The modem returns a response when the status changes.
• 2 — Enable unsolicited network registration and location information results. The modem returns a response when the registration status or additional network information changes.

The module returns OK when it sets the mode. It returns ERROR if the command fails.

Factors contributing to SIM failure to register on the network may include:

• Missing network coverage
• Denied network access
• No valid roaming agreement between the home network and currently available operators

Example

Set the mode:

AT+CREG=2
OK

Read the registration status:

AT+CREG?
+CREG: 2,5,"54DB","0F6B0578",7
OK