Will a 4g T-mobile network work on my iPhone 4?

Any compatibility issues?

Added (1). I have ios7

I think the answer depends, if you have an iphone 4 that's from ATT, with IOS 5 or older, you can unlock it (assume it's not unlock already), so it would work with tmobile

if you have the new IOS, you can still unlock it but the unlocking would be expensive.

Like said above which carrier is the phone set for? Then an iPhone 4 actually doesn't pick up a 4G signal which is the reason they came out with the iPhone 4s so quickly. Iphone 4s can get 4G service. Iphone 4 still just runs off 3g.

Hi yes t-mobile sim will work in iphone 4 only if it is unlocked one.Else if the iphone 4 is locked to some other network provider then until you unlock you can't use it with any GSM sim… You can easily unlock your iphone 4 using sites like http://www.simpleunlocking.com/apple-iphone-4/rs1wp9/ they are providing remote unlocking service to unlock all model iphone from network lock… So first check that whether the service is available for your country and network provider. If yes then pay for it and unlock your iphone 4…