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Here is my fix for the 4s with OtterBox

I can see this is an older thread, but I stumbled on it so I imagine other will still too. I was actually looking for a fix for the 5s with OtterBox.

Anyway I had my Beats Studio HD an iPhone 4s with an OtterBox Defender Series. The 4s has the headphone jack on the top left corner of the phone. The case has a flap that covers that jack. If you inspect the flap and how it fastens itself shut, you will see that it kind of notches in to a hard plastic corner. I decided I could get by with that flap only latching on one side, and I used a dremel tool to file down the hard plastic corner closest to the port. If you are doing this at home, remove your device first. Most people know this, but I feel I should say that anyway. It worked very well for me and I never had any issue with the integrity of the case being compromised. I imagine you could use a file, maybe even some really rough sandpaper to get this done.

Now that Apple has moved the headphone jack to the bottom, the OtterBox case has been remodeled, the fix isn't quite as easy. May still try something, but I really don't want to have to add an adapter.
 
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