LG G4 Unlocked

Hello,

I just purchased a LG G4, it is locked to T-mobile. How can I unlock this in a timely manner?

I tried the "unlock" app, but that said it "failed"

Also, I do not have any friends who have tmobile to help me, by putting their SIM card in it and then using the "unlock" app.

Do I have any other ways to do this, besides paying online? Is there a way to install some sort of Custom ROM that also unlocked the SIM?

Thanks a lot!