A week after its launch, the iPhone 4S is a hit and seems ready to stay in the spotlight for quite some time. Even with everyone talking about the new handset, its predecessors are still going strong. For the first time, AT&T is currently offering an 8GB iPhone 4 for $99, and the iPhone 3GS for free (with a new 2-year contract for both).

Ralph de la Vega, CEO of AT&T Mobility, held a conference call with analysts to discuss how the price drop of older iPhones is affecting customers.

“We have another device that I think is going to dramatically change those people that are on smartphones and quick messaging devices, the [iPhone] 3GS, which is free with a 2-year contract. We’ve seen a tremendous, tremendous demand for that device even though it’s a generation old. And actually, we’re getting more new subscribers coming on the 3GS on the average than other devices. So we also have an inventory sold out on that device.”

AT&T and their customers alike can benefit from the free 3GS offering. The iPhone 3GS is great for someone who has never had an iPhone. It even supports iOS 5! New adopters should go to their local AT&T stores soon, as the 3GS is out of stock on AT&T’s online store.

With the holiday season quickly approaching, we can expect to see new iPhones in the hands of many, whether it be the 3GS, 4, or 4S.