So its not the phone company running things.

When they started you could get 2.5 on a high yield so the 1% on balances above 4 wasn't a great deal. However, all those have come down to under .5 and T-mobile has stayed the same.

The transfer can be from your normal bank and you can transfer it out and you still get the 4%. It seemed a little sketch at first but its been no different than any other online high yield savings. They designed it to be used as your main bank, but I haven't used them for that.