T-mobile not working, says I need GPS update

I'm trying to move to T-mobile but I get the message below when starting the app even though I do already have GPS installed. Any suggestions?

"update google play services...t-mobile won't run without google play services, which are not supported by your device."

To be clear - you're getting the error trying to run the T-Mobile android app? That app is not required to use T-Mobile phone service.

Ok great, I didn't know that.