Can I use a t mobile sim card in a iphone 3 from on my T-Mobile account?

Can I use a t mobile sim card in a iphone 3 from on my T-Mobile account?

Yes you can but in order for you to use it the iphone 3G which i'm assuming you have must be unlocked first so it'll support it to do unlock it you must jailbreak it and once it's unlocked you can install the sim card. To install it take a paper clip and look for a tiny hole at the top near headphone jack and stick it in there to open the sim card tray where you can put it in afterwards. You may need to reboot after but once you do you should see the T-Mobile Logo and btw
They do have the IPhone 5 for T-Mobile now no annual contract.