Now that T-Mobile has a 3g network, will an unlocked iPhone 3g work on it?

[ExpertTechAnswers]

Also, if I use an unlocked iPhone 3g on the T-Mobile network, will I still have to pay for the unlimited data plan or can I use it just like a regular phone? Also, will the G1 plan work for the unlocked iPhone 3g?

[Unregistered]

If the iPhone 3G is unlocked, It will definitely work with T-Mobile SIM card. But you cannot use it just like a regular phone. You have to add a data plan for it. T-Mobile uses a different frequency. So, be careful while buying an unlocked iPhone. Certain temporary unlocking methods would give iOS problem while working with T-Mobile SIM card. Also temporary unlocked iPhone will get relocked on future iOS update. So it is better to get a network locked iPhone and unlock it yourself permanently.
To unlock an iPhone 3G, you can visit SimpleUnlocking.com and get the remote unlocking service. This method of unlocking is safe, simple, affordable, quick and permanent. It doesn't require a jailbreak too.