US Sim Card...can someone explain this to me please

I am going to stay at my parents in New York for the month of August, and I would really like to be able to use my Blackberry while I am there. I am on O2 and have a BB Torch. I know you can buy a US Sim card while there, but I am just not sure how this whole thing works!! I would like to be able to BBM with my sister, maybe have a US number so I don't have to borrow my dads crappy old mobile phone, use facebook, upload photos etc.

How does this work? How do I get a US Sim card? Can I do this on an O2 Phone? Any help or experience would be appreciated! Thanks in advance!

You can messenger your sister with your UK sim card. Blackberry messenger is free no matter where you are. I have tried a couple different providers in the US and a US sim would not work in my UK phone.

racheee...I am doing the same thing.
1. I have a google voice # which is how I do texting to US peeps it forwards to my iphone google email and I can reply from there.
2. I am getting a US sim card for my iphone from mrsimcard - I will be there for 6 weeks and I am paying for 2 months which is 160 bucks unlimited calls/texts/data.

I have O2 as well and a forum on a travel site pointing me in that direction.  My iphone is now unlocked so I am going to test it with another sim card I have here but according to peeps it should work no problemo.

The reason for the google voice # is no matter what # they give you over the years for a sim you just use your google voice # and redirect it to where you want (US only).

hope this helps a bit!