US number-two operator AT&T has upped its Q4 and full-year smartphone sales forecasts, in part due to a replenishing of iPhone 5 stocks.

Speaking at a conference in New York yesterday, Ralph de la Vega, CEO of AT&T’s mobile arm, said that the firm had already clocked up 6.4 million smartphone sales in the first two months of Q4, compared to shipments of 9.4 million in the entire period last year.

This allowed de la Vega to up AT&T’s full-year smartphone sales forecast by 1 million to 26 million units.

“Traffic in stores has been strong,” he said, notes a Financial Times report.

The ‘holiday shopping’ quarter is usually the strongest for smartphone sales, though there were fears that US operators could suffer from weak stocks of the iPhone 5, which launched in September.

AT&T reported weaker than-expected postpaid net additions in Q3 as the majority of iPhone sales in the quarter went to existing customers, where it said there was “considerable pent-up demand.” However, de la Vega said yesterday that AT&T’s inventory is now “in good shape,” following an “initial spike” in demand.

As well as the iPhone 5, de la Vega also pointed to strong sales of Android-based smartphones such as the LG Optimus G and HTC One X, and said he was “really excited” about sales of its Windows Phone devices, including the Nokia Lumia 920 and HTC 8X.

Figures published by IDC earlier this week forecast that smartphone sales will grow 45.1 percent in 2012 to reach 717.5 million units. This is despite the overall mobile phone market growing by only 1.4 percent (to 1.6 billion), the lowest annual increase for three years.