Is it possible to use instant mastering on a phone?

Yes, go to https://sfrbeats.com/pricing/Instant+Mastering - order it - then it will direct you to the page to upload your song. It will take care of it from there! Make sure your song is mixed but NOT mastered before you upload it.. meaning make sure your song sounds the way you want it (fades and all) but don't put loudness on it... the Instant Mastering will do that for you.