The frenzy for the Apple iPhone 4, which officially goes on sale at 7 a. m. June 24, became evident on Tuesday - the first day of the pre-orders - with the company having logged a `record' over 600,000 early orders for the device.

According to reports, the number pf pre-orders for the forthcoming iPhone 4 is, by far, the largest ever taken by Apple in a single day. With the pre-order frenzy beating all expectations, the computer systems of the company as well as AT&T - the exclusive iPhone carrier in the US - were virtually jammed.

AT&T reportedly sold out all the handsets it had allocated for pre-orders, as it received nearly "ten times" more early orders for the new iPhone vis-a-vis the pre-launch orders for the model launched last year. In fact, the higher-than-anticipated pre-orders for the iPhone 4 forced the carrier suspend the sales of the device on Wednesday.

Acknowledging that the iPhone 4 pre-orders have been notably brisk, Apple said in a Wednesday statement: "Many customers were turned away or abandoned the process in frustration. We apologize to everyone who encountered difficulties."

Noting that the iPhone 4 is a significant upgrade and tech analysts expect the stock to sell out quickly, Roger Entner, head of telecom research for Nielsen, said: "Consumers want the next big thing, and right now, that's the smartphone."