To plug the headphones into the phone you have to leave the flap open .
I would recommend this to a friend!
Response from otterbox.comBy OtterBox, Customer Service Team, November 6, 2018
Hi Charlie,
We're glad to hear that your experience with the Defender series so far has been matching up to expectations so far! True - the Defender does have a rubber port cover that folds over the audio jack. In order to plug in your headphones, you do have to open the port cover.
If you have any other questions or comments going forward, please feel welcome to call our wonderful Otters at 1-855-688-7269. They're always delighted to provide assistance!
Replaced an old otter box with this one. I was afraid it might be be too bulky. After an initial tussle wrapping it around my iPhone 6, (directions were minimal) it’s perfect! Phone looks brand new.