Can an iPhone 4s work on t-mobile unlocked?

I was wondering if I could buy an unlocked iPhone 4s from ebay and put my T-Mobile sim card in it, I have 4g, will it work? Will I be able to use it as soon as I put the sim card in it?

Ask the guy if he got 3g or 4g but you should get 3g because most phones have 3g

Yes you could, but don't expect 4G (not immediately anyway).

TMobile is getting the iphone in 2013