Thank you for your interest @smgs 
I am using a soracom IOT multioperator Simcard, and yes I am using an aerial and yes I know I can tag code BUT there is a BUG in the interface here : depending on the code you want to post, some part of it might not be included in the code box.
Even though the battery had a voltage >4V, I changed it with anew one and now AT+CREG is not freezing.
Here is the return for "AT+CIND?"
AT
OK
AT+CIND?
+CIND: 5,2,1,0,0,0,1,0,2,0,0,1
OK
Also the gsm scan :
Scanning available networks. May take some seconds.
AT+COPS=?
+COPS: (2,"F SFR","SFR","20810",2),(1,"Free","Free","20815",2),(1,"F-Bouygues Telecom","BYTEL","20820",2),(1,"Orange F","Orange","20801",2),(2,"F SFR","SFR","20810",0),(1,"Orange F","Orange","20801",0),(1,"F-Bouygues Telecom","BYTEL","20820",0),,(0-6),(0-2)
OK
> F SFR
> Free
> F-Bouygues Telecom
> Orange F
> F SFR
> Orange F
> F-Bouygues Telecom
Current carrier: AT+COPS?
+COPS: 0,0,"F SFR",2
OK
F SFR
Signal Strength: AT+CSQ
+CSQ: 16,3