Industry analysts are lifting their predictions for the number of iPhones Apple will sell this quarter, with one expert now placing the figure as high as 30 million units.

UBS analyst Maynard Um made the prediction after carrier AT-T announced it was expecting its best smartphone quarter ever, largely on the back of the iPhone 4S. Um's previous estimate was 28 million.

Apple itself has promised to set an iPhone record. The previous peak was 20.3 million, in the quarter ended June 25 2011, while in the most recent quarter sales dipped to 17.1 million due to anticipation of the iPhone 4S. Apple later revealed that 4 million of those devices were sold in its first weekend on sale – and that was only in seven countries.

The news isn't all good for Apple, though, with some analysts dropping their predictions for the iPad. Sales of the market-leading tablet device are expected to reach between 12 and 13 million, an improvement on the 11.1 million seen in the previous quarter, but nothing like the growth we're used to seeing from the tech giant.

Apple shares are trading at US$393.37, above the US$369.80 low seen when founder Steve Jobs passed away, but down from the heady US$422.24 high seen immediately after the iPhone 4S was released.