Analysts believe that Apple will announce sales of anywhere between 25 and 35 million iPhones in its next quarterly financial report.
Fortune has compiled a range of predictions from 40 different analysts, with estimates of how many handsets Apple sold between 25 September and 31 December 2011 varying wildly.
Fortune has differentiated between what it calls 'professional' analysts - essentially, those working on Wall Street - and 'independents', which it describes as "an assortment of bloggers, enthusiasts and individual investors".
The professionals are a lot more cautious in their predictions, with the average estimate being 29.74 million units, which would represent a year-on-year increase of 83 percent.
The independents are much more positive about iPhone sales in the last quarter, with an average of 33.42 million units - a year-on-year increase of 106 percent.
Individually, Posts At Eventide's Robert Paul Leitao (Independent) has the highest prediction of 35.75 million, while Hendi Susanto of Gabelli & Co (Professional) offers the most conservative estimate of 25.16 million.
Apple will reveal the real figure on 24 January in its quarter financial results call with analysts.