How to get 4g on tmobile with my IPhone 4?

I have an iPhone 4 and I have tmobile. Right now I have tmobile edge and I heard that once the iPhone 5 comes out, tmobile users that have an unlocked iPhone can get 3G or 4g instead of having E for their data. Is there a way I can get 4g or would it still not work?

If your phone was made to use 4G then you will be able to, but if your phone is not build with the 4G then there's nothing you can do except to upgrade because 4G is not a software thing that you can just install a program and make your phone a 4G phone. 4G is hardware built into the phone.

The only iphone that can use the 4g network is the iphone 5. Why is that? Because it is the only phone that has the 4g LTE chip set. Without that chipset you can't get access to 4g. Therefore your iphone 4 will NOT be able to access any 4g network - on tmobile or any other.