GPRS Shield SIM900 on Arduino Uno R3

Products & Technology Shields
#1

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 (http://www.seeedstudio.com/wiki/index.php?title=GPRS_Shield_v0.9b#Getting_Started_-_Fun_with_AT_Commands), I do get the following when I am switching on the GPRS shield:

RDY

+CPIN: NOT INSERTED

+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?

Thanks!
Martin

#2

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

#3

Does your SIM has a pin code ?

#4

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?