By AppleInsider Staff

Published: 08:15 PM EST

Apple's over 160 national retail stores will follow a similar procedure to those of AT&T's on June 29, closing for approximately 90 minutes in late afternoon before reopening with the first iPhones for sale.

The plan was documented in an internal AT&T memo sent to store managers last week regarding organizational procedures for the Apple product launch. Store managers on both sides are preparing for unusually large levels of traffic and have been told to forewarn their landlords and acquire stanchions.

"In order to prepare for the launch we plan to close our stores 1 1/2 hours prior to launch time, at 4:30 PM," the memo said. "If the landlord questions your plan to close the store from 4:30 - 6:00 PM, explain that all AT&T and Apple stores nationwide intend to follow this plan."

Once reopened, AT&T stores will operate till 10:00 PM on the eve of June 29, the memo added. It's unclear whether Apple stores will follow a similar plan, or have separate sets of hours.

Similarly, it's uncertain how many consumers will actually turn out for the first-day sale, especially when it comes to plunking down at least $499 for the cheapest iPhone Apple plans to sell. AT&T chief executive Stan Sigman, however, is confident that all the hype is justified.

[iPhone] is the largest commercial product launch in the history of electronics," he said during a graduation speech at the West Texas A&M University last month.

That's just part of the reason AT&T stores, like Apple's, will also reportedly be adding a number of temps to their staff ahead of the frenzy. Many of the AT&T hires will remain at their stores throughout the summer.