Geeetech

I have similar problem and I dont get access to gsm network. Reason is bad network, because I have problems with my samsung phone in this area.

Anyway, I tested my gsm shield as far as I could, until I go home, where network will be much better.

To check will SIM work run next AT command :
at+cpin ...

I found my problem. GSM Shield wasn't used fixed baud rate. It was set to use auto-baud rate and that's why it wasn't answer as I expected. Baud speed syncronate wasn't get up and I too fast expected that my shield was broken.

AT+IPR=?

+IPR: (),(0,1200,2400,4800,9600,19200,38400,57600,115200)

OK ...

I understand what you mean. Now I have hunted problem and software port D7/8 are between arduino and GSM shield. Serial port D0/1 are only used for debug.

With this code I found that some reason I have GSM shield where baud rate dont stay in same speed.
#include <SoftwareSerial.h>
SoftwareSerial ...

It seems that baud rate of GSM shield v1 changing by it self or GSM shield cant keep it right. Next thread I told that I hunted baud rate to get OK from shield. Next time rate wasn't always same.

http://www.geeetech.com/forum/viewtopic.php?f=16&t=15855&p=20549#p20549

I must say that I am ...

I have similar problem, but I get response for AT. Only by testing different baud rates. Some reason speed of shield changing by itself or what happens?

I used this code for hunting right baud rate. Do I have problem with power or shield?

#include <SoftwareSerial.h>
SoftwareSerial SIM900(7, 8 ...

Old post, but I found it worth of nothing and I want to open questions why JP need to weld? That JP is used only for get D9 to working to start and shutdown GPRS Shield by arduino
Software Triger; If use this way to power up the GPRS Shield, JP need to be soldered, then Digital Pin 9 of the Arduino ...