Sim900 GSM/GPRS shield from ebay

Hello, I know there are other posts about this topic but, I am such a beginner that they are all way over my head. I need an explanation similar to that of a 5 year old. So, I apologize for the repost.

Background I purchased this shield from ebay (http://goo.gl/ikirM) Attempting to use it with an UNO R3 I got an AT&T go phone with a 3G sim card

After following the provided wiki (http://www.geeetech.com/wiki/index.php/Arduino_GPRS_Shield) it is clear that something beyond my knowledge is wrong.

I JUST WANT TO SEND A DAMN TEXT.

Does it require a 2G sim card and I have 3G? RX and TX are pin 7 and 8. I have the jumpers on the SWserial side. What is this com tool I keep reading about and why doesnt it exist for mac? There seems to be a million libraries, which one do I need? Indicator lights -RED is solid - GREEN flashes 3 times/second.

I know its a drag to go through this with such a beginner but please, I am in need of some help.

New developments have been made. Ive figured out the whole serial communication bit and am now having some connectivity problems. After firing up the shield i get the following read out.

+CFUN: 1

+CPIN: READY

+PACSP: 0

Here are the results to CREG, CBAND and COPS.

AT+CREG?

+CREG: 0,0

OK AT+CBAND?

+CBAND: GSM850_MODE,ALL_BAND

OK AT+COPS?

+COPS: 0

OK When I try to send a text, i get the following. AT+CMGF=1

OK AT+CMGS = "+1404****863"

ERROR

Any suggestions to get it working?

Hi, The GSM shield you have purchased uses a SIM900 chip. This chip only works with 2G SIM's and will not work with the 3G network. I had the same problem myself until I worked this out.

The specs are listed http://www.elecfreaks.com/store/4-frequency-ultra-gsmgprs-module-sim900-p-109.html it reads Compliant to GSM phase 2/2+ as far as I can tell this means that SIM900 only supports 2G networks. I have managed to get my shield which is also based on the SIM900 to work with a 2G SIM but it will not recognise the network with a 3G SIM.

Indicator lights -RED is solid - GREEN flashes 3 times/second.

The Green led will be the Network status when it is connected to the network correctly it should flash only once every 3 seconds.

This application note may be of interest http://www.otto.co.za/store/dataSheets/product/1be0954814643cba0bebabfc07f09a73.pdf

I have collected some manuals for the SIM900 http://www.rupert.id.au/tutorials/arduino/SIM900/ which may help

If you need a 3G sheild take a look at this http://www.cooking-hacks.com/index.php/3g-gprs-shield-for-arduino-3g-gps.html

Good luck