I can't play songs when using LTE

[littleredwolff]

I'm a Spotify Premium subscriber and I can't play songs that aren't downloaded on data. I have T-Mobile and an iPhone SE. If I'm using data and open Spotify, a message will appear the the bottom of the screen that says "you are offline". I have friends with Androids and playing music offline works fine for them, so I didn't know if it was me or an Apple thing. If not, I'd like to know hot to fix this. Thanks!