SIM900 GSM/GPRS : AT+CGATT returns ERROR +CREG: 3

[vvv1234]

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

 

[FvM]

- String parameters should be included in quotations marks
- What's the colon after CGATT=1?

Generally, turn on extended error messages to understand what's going on.

 

[vvv1234]

- String parameters should be included in quotations marks
- What's the colon after CGATT=1?

Generally, turn on extended error messages to understand what's going on.

Hi,

Colon at the At command is my type error. It happens only when there is a weak signal,
Even some times with weak signal activation will be OK and some times not OK.
May i know, how to enable extended error messages?

AT+CREG=1
OK

AT+CGATT?
Call Ready
+CGATT: 0
OK

AT+CGATT=1
ERROR
+CREG: 3

Regards,
Venkat

 

[FvM]

Review AT manual for AT+CMEE command.

 

[vvv1234]

Hi FvM,

Here is the logs for your reference :


AT+CMEE=1
OK

AT+IPR=9600
OK

AT+CSCLK=0
OK


AT+CIPSTATUS
OK
STATE: IP INITIAL

AT+CSTT=m2minternet
+CME ERROR:107
Call Ready


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: 0

AT+CSTT=m2minternet
+CME ERROR:107


Since AT+CGATT is not successful, i have tried firing the commands again from the start then at the end i get registration denied for AT+CGATT command.
AT+CGATT=1
ERROR
+CREG: 3


Thanks,
Venkat

 

[FvM]

Did you review the meaning of CME error 107?

Apparently you are experiencing a network/subspription problem, not particularly related to SIM900 or AT commands.