The modem is always reseted before inserting / switching sim cards.
Here isthe complete list of commands / answers of the modem initialisation before I get the error :
+WIND: 3
+WIND: 13
AT+CFUN=1
+WIND: 3
+WIND: 13
ATE1
OK
AT+IFC=2,2
OK
AT+CMEE=1
OK
AT+CPIN?
+CME ERROR : 515
The answers to AT+WFM=2 is
+WFM: "MONO900",0,0
+WFM: "MONO1800",0,0
+WFM: "MONO1900",0,0
+WFM: "BI9001800",0,0
+WFM: "BI9001900",0,0
+WFM: "MONO850",0,0
+WFM: "BI8501900",0,0
+WFM: "QUADBAND",1,0
+WFM: "EFR",1,0
+WFM: "HR",1,0
+WFM: "DTXDATA",1,0
+WFM: "DATA144",1,0
+WFM: "SIM3VONLY",0,0
+WFM: "SIM1V8ONLY",0,0
+WFM: "SIM1V8AND3V",1,0
+WFM: "SIMREMOVE",1,0
+WFM: "OFFWHENUNPLUG",0,0
+WFM: "SWITCHATT",1,0
+WFM: "CPHS",1,0
+WFM: "SIMSPEEDENH",1,0
+WFM: "LOCA",0,0
+WFM: "AMR",1,0
+WFM: "NT_6K",1,0