EFCom/GPRS Shield Tutorials restarting

I am using EFCom/GPRS Shield which is a GSM shield using SIM900, as these GSM modules consume a lot of current, I decided to buy 12V/2A adapter.

however, the GSM shield keeps restarting even though its connected to the arduino (the STA (status) pin turns off and on while try to connecting to the network)

here is a picture of my arduino and the adapter,

here is a picture of the LEDS of this shield

the problem is:I can not connect to the network - the NET led is blinking every 800 ms which means the shield is trying to connect to the network (it should be blinking every 3s to be connected to network) - and while the NET LED is blinking, the STA (status) LED turns off and on from time to time which means the shield is restarting

can you advise on this ?

in case the picture is not showing, here is the link:

https://goo.gl/photos/DB52P2tPJUnUtwt97

Did you found the solution for this problem? I have the same issue.

Powering 3.3volt or 5volt electronics with a 12volt supply is generally a bad idea. 2/3 of the power is converted into heat in the voltage regulator(s). That makes them shut down.

Try a 7.5volt or 9volt supply.

Those shields migh "only" use 300mA in receive mode. and up to 2Amp while transmitting. Post links to the exact parts. Leo..