Will call usually opens between 1 PM and 3 PM prior to the show on the day of the concerts. Mizner Park Amphitheater does not have a permanent box office.
The gates generally open an hour before the concert so I image staff will be there even earlier.
If it is a free concert, no calls are necessary. If is not, phone calls should be available soon.
You should be fine just before the show. I believe they are there up to an hour before.
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