Hi,
SIM900 GPRS device attach to the network fails when there is the weak signal.It happens some times only, Once it happens then device need to reboot to make it work again. I my case i can not reboot the device because device is inside the vending machine, so power is on for all the times.
AT+CGATT=1 returns an error +CREG: 3( registration denied).
But AT+CREG? returns 1,2
power supply specification : 12V/1A
Here is my AT comands
ATE0:
OK
AT+CSQ
+CSQ: 8,0
OK
AT+IPR=9600
OK
AT+CSCLK=0
OK
AT+CIPSTATUS
OK
STATE: IP INITIAL
AT+CSTT=m2minternet
ERROR
AT+CIPSHUT
SHUT OK
AT+CFUN=0
+CPIN: NOT READY
+CREG: 0
AT+CFUN=1
OK
AT+CREG?
+CREG: 2
+CREG: 1,2
OK
AT+CREG=1:
OK
AT+CGATT?:
Call Ready
+CGATT: 0
OK
AT+CGATT=1:
ERROR
+CREG: 3
Regards,
Venkat