Do I need a sim starter kit if I already have a sim card?

I had the galaxy s1 to begin with. It broke so I just switched the sim card to a blackberry bold I already had. I never switched to a blackberry plan so I can't use any of the blackberry apps unless I have Wi-Fi connection. I'm going to purchase in an iphone 4s next week.

My question is: do I need to buy the sim starter kit even if I already have a sim card? I have a family plan with 4 other phones so it is not going to be prepaid. If I do get the starter kit will my number change? I have T-mobile.

No you don't, you can just switch the sim over.