Jailbreaking and unlocking 4S

Hey
So I currently have a iPhone 4S that is able to use T-mobile, which suggests that it has been unlocked (I am not sure how it was unlocked)

well anyways, I have been wanting to jailbreak it, but I have discovered that Jailbreaking would cause the unlocking to be gone, therefore I would have a jailbroken iPhone 4s that cannot make calls...right?

So I just want to know if there is a way to unlock the Iphone 4s after it has been jailbroken, without using those sim cards

The Ios is 7.0.3