Analysts who slagged off the 4S are now adding millions on to their projections.
Investment bank UBS upped its estimate from 28 million to take account of buoyant sales of the device, which was launched in October. Specifically, it was responding to AT&T's announcement that it expects its best smartphone quarter ever.
UBS also raised its revenue projection to $38.5 billion, from $37.2 billion.
There is a consensus growing around the sales estimates, with Sterne Agee analyst Shaw Wu also looking at 28 million based on checks with Apple's global supply chain.
He sees iPhone remaining strong across the board, including the older iPhone 4 and iPhone 3GS. J.P. Morgan also recently revised its forecasts to predict Apple as shipping 28 million iPhones this quarter.