Siemens TC37 Module At Command Reference page 109

AT Command Set
Unsolicited result code
If <n>=1 and there is a change in the ME network registration status:
+CREG: <stat>
If <n>=2 and there is a change in the ME network registration status or a
change of the network cell:
+CREG: <stat>[,<lac>,<ci>]
Reference Note
GSM 07.07 Optional parameters will not be displayed during a call.
Example
AT+CREG=2
OK
AT+COPS=0
OK
+CREG: 2
+CREG: 1,"0145","291A"
TC3X_ATC_01_V04.00
Activates extended URC mode.
Forces ME to automatically search network
operator.
URC reports that ME is currently searching.
URC reports that operator has been found.
Page 109 of 204 29.05.2002