Forecasting iPhone units sales for Apple's 1st fiscal quarter is quite a challenge. Coming off a sensational September quarter performance, there are no historical data points that can be relied on to develop an earnest estimate for the December quarter.
I expect an expansion of global channel inventory from about 2 million units to about 3 million units as many more global points of purchase become available and product is provided to meet the demand of consumers. I also expect the chronically constrained supply that had hampered sales to have been resolved in October.
Still, the pace of consumer sales and activations from the September quarter should have carried into this quarter even before holiday seasons sales become a factor.
For these reasons I'm currently estimating 8 million iPhone units sold in the December quarter, subject to revision as anecdotal information and sporadic published reports provide evidence to the pace of sales between now and the end of the year.