Apple and AT&T have issued statements on the constrained availability of iPhone 4s and on shipping delays.

Here's Apple's statement: "Yesterday Apple and its carrier partners took pre-orders for more than 600,000 of Apple's new iPhone 4. It was the largest number of pre-orders Apple has ever taken in a single day and was far higher than we anticipated, resulting in many order and approval system malfunctions. Many customers were turned away or abandoned the process in frustration. We apologize to everyone who encountered difficulties, and hope that they will try again or visit an Apple or carrier store once the iPhone 4 is in stock."

Here's AT&T's statement: "iPhone 4 pre-order sales yesterday were 10-times higher than the first day of pre-ordering for the iPhone 3G S last year. Consumers are clearly excited about iPhone 4, AT&T's more affordable data plans and our early upgrade pricing.

"Given this unprecedented demand and our current expectations for our iPhone 4 inventory levels when the device is available June 24, we're suspending pre-ordering today in order to fulfill the orders we've already received. The availability of additional inventory will determine if we can resume taking pre-orders.  

"In addition to unprecedented pre-order sales, yesterday there were more than 13 million visits to AT&T's website where customers can check to see if they are eligible to upgrade to a new phone; that number is about 3-times higher than the previous record for eligibility upgrade checks in one day. We are working hard to bring iPhone 4 to as many of our customers as soon as possible."