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16.7
GPRS - GSM modem CREG result codes
As visible in the RS232 data dumps one of the command sent to modem is “at+creg?”
Depending on the connection that has been setup one the following responses can be seen:
+CREG: mode, status e.g. +CREG: 0,2
Mode
0
Disable network registration unsolicited result code (default)
1
Enable network registration result code
2
Enable network registration and location information unsolicited result code
Status
0
Not registered, Mobile Equipment is not currently searching for a new operator.
1
Registered, home network.
2
Not registered, Mobile Equipment currently searching for a new operator to register to.
3
Registration denied.
4
Unknown.
5
Registered, roaming.
In the TestGprs or TestEmail it is common to see a number of +CREG:0,2’s followed by a +CREG:0,1 when successful or +CREG:0,3
when the SIM card is denied or depending on the local operator the combination of SIM card and data modem is denied.
When in doubt it can help to put the SIM card in a smartphone and try to dial and get mobile data. This way you have also checked
the PIN code.
In some countries standard SIM cards for voice and data are banned from working in data only equipment. Please consult your
local operator for detailed information.
Describing all commands is not in the scope of this manual but an internet search on “AT Commands Reference Guide for Cellular
Modems” will deliver useful results for in-depth research.
