We know some of those 183 million are the kind of customers who buy a new iPhone each time one appears, but we also know that not every iPhone customer can.
We also know that US carriers have loosened up a little and are more prepared to allow customers to upgrade more frequently than every two years. This began last year, meaning iPhone 6 owners are among the last to find themselves locked in. Some may go to Android, but we also know that millions more migrate from Android to iPhone.
What does this mean?
This isn't an exact science - far from it, but looking at the data it seems Apple could soon benefit as tens of millions of iPhone 6 owners find themselves liberated from their contract and eager to purchase the much-improved iPhone 7.
It's hard to predict - there are a range of factors that may dampen interest, from economic melt down to the loss of the headphone port, but even one cautious estimate from Mizuho Securities analyst, Abhey Lamba predicts between 178-230mm iPhone sales. Dawson's additional insights mean those target figures seem all the more realistic.
The secret sits with Apple, of course, as no amount of fortune telling will mean anything until the company takes the wraps off the new iPhone 7 on the seventh next week. Until then, we'll keep on speculating.
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