Will a T-mobile sim card work with a unlocked Iphone 3g?

Yes. If you buy an unlocked iPhone 3G, you can definitely use a T-mobile SIM card with it. But before buying an unlocked iPhone make sure from the seller, how was the iPhone unlocked. Certain unsafe unlocking methods would give iOS problem while working with other SIM cards. Temporary unlocking methods will also relock the iPhone on your future iOS updates. Resulting in more expense. So it is better to buy a network locked iPhone for low cost and unlock it safer and permanently by yourself. You can unlock an iPhone using remote unlocking service. You can get the remote unlocking service for an iPhone from OnlineGSMUnlock.com This method of unlocking is safe, simple, affordable, quick and permanent. It doesn't require a jailbreak too. You can also visit MobileUnlockGuide.com to get the free unlocking instructions for an iPhone 3G. Good luck.