Speaking during the ongoing Apple v Samsung trial, senior vice president of worldwide marketing at Apple, Phil Schiller, revealed that when assessing sales for a new iPhone model, the company would base predictions on the fact that: "Each new generation sold approximately equal to all previous generations combined."
Asymco started its analysis by working out the estimated iPhone sales history of each generation, and then calculating the cumulative totals of those models.
The results showed that the iPhone 3G sold nearly four times the amount of original iPhones sold by Apple, and that the iPhone 3GS went on to sell 1.6 times more units than the iPhone 3G.
The iPhone 4 has just about outsold the original iPhone, the 3G and the 3GS's sales put together, but Asymco notes that the model could continue to sell, adding to that total.
The iPhone 4S has currently sold more than the iPhone 4 by a fraction, but is only half way towards beating the cumulative total sales of its four predecessors.
Asymco predicts that Apple will sell enough iPhones 4S units by September to put the model two thirds of the way towards beating the cumulative sales of the original iPhone, the iPhone 3G, iPhone 3GS and iPhone 4.
It is expected that the iPhone 5 will launch in September, but the iPhone 4S is likely to continue to sell after this date, probably at a cheaper price, so could reach its target of 162 million units sold.
This would put the cumulative total of all five current iPhone models at more than 263 million units (if you include the predicted iPhone 4S sales expected to be made before the iPhone 5 is launched).
So, that leaves us with Apple's iPhone 5 sales target: more than 263 million units.
A previous analysis from Asymco resulted in the prediction that Apple would sell 165 million iOS units in the last half of 2012. Asymco thinks that 102 of those units will be iPhones. "Taking that forecast forward and assuming a 60 per cent growth rate, I currently have abut 200 million iPhones over the next twelve months," reads the report. "If 85 per cent of those are the next generation, that yields about 170 million iPhone 5s through mid 2013."
Asymco points out that this estimate doesn't meet Apple's target of 263 million, but if the iPhone 5 continues to sell after the seventh generation iPhone is released, as has been the case with previous models, Apple could break the 200 million mark. "There is also the question of whether the "mix" will begin to favour the older generations more," the report continues. "If that's the case, we might see version "5" meet its target."