GPRS Shield SIM900 on Arduino Uno R3

Newbee question:
I do have a Seeedstudio GPRS Shield (SIM 900) mounted on an Arduino Uno R3. When I do follow the “Getting started” section from the wiki page (, I do get the following when I am switching on the GPRS shield:



+CFUN: 1

And the NetLight keeps flashing.
SIM card inserted, tried with and without external power.
Does anybody do have an idea of what is going wrong?


you can try used another Sim card ,if no effect , with a multimeter to determine whether the pin between SIMHOLD and SIM900 disconnected ?

Does your SIM has a pin code ?

I had a SIM with a PIN, but I inserted the SIM into a regular Phone and switched PIN verification off, re-inserted into the GSM module but still receive this error.
Do I have to place the CR2013 battery into the battery slot?