Can I use Ultra mobile sim card in T mobile? Ultra mobile runs on T mobile network. I do not want to change my operator and get this amazing phone.
Best answer by smplyunprdctble
It's probably based on the agreement between the MVNO Ultra (who I've never heard of, but that means nothing) and T-Mobile.
I can tell you that Walmart Family Mobile plans (powered by T-Mobile) do let locked T-Mobile phones on their network.
I think that's the advantage of StraightTalk as well -- you don't need to be unlocked if you pick the carrier of the phone you have (keyword is think)
So, there's a good chance that if Ultra is a T-Mobile MVNO you don't need it unlocked. Easiest test? Find someone with a T-Mobile branded phone that's not unlocked (if they don't understand then it's probably not unlocked) and pup your Ultra SIM in it. You may even be able to hop into a T-Mobile store and borrow an employee's device to test it. Especially if you are intent on purchasing a device, they'll probably be more helpful.