iPhone trade-in surge ahead of 4.7 and 5.5-inch models tipped for Sept 9

Apple will have a "tremendous" opening of the iPhone 6, buyback vendors tell Computerworld US.

Their predictions are based on consumers taking advantage of 30 day price lock-in guarantees for trading in their their old smartphones.

Two new iPhones are tipped to be unveilled at an Apple event scheduled for September 9. Release is expected about a month later.

The Wall Street Journal, Bloomberg and others are reporting the two new iPhones will both have bigger screens, based on leaks from Apple's contract manufacturers.

One of the most well-connected Apple blogs, Daring Fireball, notes, "Throughout the entire rumor cycle for this year’s new iPhones, we’ve been inundated with reports of two new screen sizes, 4.7 and 5.5 inches. But while the physical sizes of these displays leaked early and often, the exact pixel dimensions have not.

"At this point, there’s too much smoke around the 'two new iPhones, 4.7- and 5.5-inch' narrative for there not to be a fire."

Apple's current flagshop iPhones, the 5s and 5c, have 4-inch screens. Most top-end Androids have 5.1 or 5.2-inch displays. 

350% jump
"There's tremendous pent-up demand for a larger-screen iPhone," Jeff Trachsel, chief marketing officer at NextWorth, a US company that buys used consumer electronics devices, including tens of thousands of iPhones each year, and resells them domestically or overseas, told Computerworld.

Mr Trachsel and others based their opinions on an increase this week in the number of quote requests for used iPhones.

"We've seen a lift of about 350% from the baseline this week," said Trachsel, referring to quote volume since Monday compared to the average of the month prior to that. "That's up from a lift of 182% last year, or almost two times the acceleration."