When I used to code I'd use the Pomodoro Technique.

It helps me get tasks done more quickly and efficiently when I know I only have to focus for 45 minutes and then I get a 15 minute break.

It also helps if you're stuck on something, because when you come back to it you have fresh eyes.

Also, music without any lyrics helps me focus better than music where someone is singing. Be it Mozart or dubstep, as long as there are no words I can work with it. 😂 (I highly recommend Instrumental Core)

Finally, my phone would be in a completely different room or in my desk drawer in DND mode. I set it up so that it only rings for certain people (parents, brother and boyfriend), so no-one can bug me while I work. It's fantastic.