Arduino GSM shield

Do I need sim card if I buy Arduino GSM shield?
I am working to connect the Arduino to send email, text message etc. I have seen a video but not sure if the Arduino GSM shield comes all pre-assembled and ready to use after I interface with Arduino software or do I need a sim card? If I do, then please advise where I can get sim card?
Thanks,

Do I need sim card if I buy Arduino GSM shield?

Only if you want to send or receive calls or text messages.

If I do, then please advise where I can get sim card?

7-11 sells them.

Thank you for the reply.
Can you please write specs for the sim card so that when I ask at 7-11 for sim card they understand and Merchant give me the correct one?
Also, about the Arduino GSM shield I have inquired from a local Radio Shack (RS) retailer. RS does have in stock but again if you can provide me the specs that ensure that retailer is selling me the correct one. I am running short of time on a project , therefore getting a correct part and implementing it is the need of the hour. Thanks for your help!

Have you checked what network your local area is operating, 2G or 3G, as a lot of counties are ditching 2G which means you may need to by a GSM module or Shield that can handle 3g, which are a lot more expensive.

it is 3G. So, the one available at local radioShack (Arduino GSM shield) is not the right one?
Thanks..

The RS one and even the genuine Arduino gsm shield are only 2G .

You need to look at something like this module.

Any board you see with SIM900 or SIM808 /808 are 2G models.