AT&T, Apple servers already buckling under iPhone 4 customer load? [updated x5]

Less than half an hour after the start of iPhone 4 pre-orders, the processing system used by Apple and AT&T to sign up new customers for iPhone data plans appears to be experiencing order-stopping technical issues. Though existing line orders for the iPhone 4 appeared to be working, attempts to use Apple’s “buyiphone.apple.com” pages to sign up for new service are stalling, producing an endlessly spinning gear with the message, “Please wait while we process your request,” and/or “session expired” notices claiming a timeout on the user’s side due to inactivity.

It remains to be seen whether these ordering problems are merely a brief early hiccup, or a repeat of past AT&T account issues that marred past iPhone launches with extended service activation delays.

Update: Problems continue an hour and fifteen minutes after the start of pre-ordering and appear not to be limited to new customers, or even just U.S. customers. Unusual Apple Store errors are appearing when attempting to pre-order iPhone hardware from the United Kingdom, and readers with existing AT&T accounts are also reporting timeouts when attempting to order the iPhone 4 from Apple’s web site.

Update 2: Nearly two hours into pre-ordering, the Apple Store’s prior timeout and spinning gear errors have now been joined by a generic “oops” error that appears when attempting to place the iPhone 4 in a cart for online ordering and at-home delivery. Apple currently appears to be falling back to a semi-working system that offers reservations for in-store pickups as an alternative to the still-problematic online ordering system.

Update 3: Apple has taken the Store offline in an apparent attempt to resolve the ordering problems. AT&T’s web site was, as of several minutes ago, processing iPhone 4 orders properly for existing customers but not yet taking orders from new customers. Like Apple, AT&T was accepting orders only for black iPhone 4 models without an option for white ones. As of now, AT&T’s site is down with a “currently doing maintenance” message.

Update 4: Both Apple’s and AT&T’s pre-order sites have returned. Reports from readers indicate that some AT&T iPhone 4 orders were abruptly cancelled for reasons unknown; we’d advise checking your e-mail account for cancellation notices in the event that you ordered from AT&T earlier this morning.

Update 5: Five hours after pre-orders started, both Apple’s and AT&T’s web sites are continuing to experience major service interruptions and order processing failures. We’ll update this story again when the problems are resolved.