Horace Dediu of Asymco is good with numbers and his latest work uses this skill to look at discarded iPhones in the US. Dediu takes monthly comScore data and quarterly activation data provided by the wireless carriers to calculate the install base of the iPhone in the US. His number crunching and resulting graph shows the number of new activations and the calculated number of iPhones being put out of service each quarter.
According to Dediu, the discard rate, which is the number of phones being discarded over the number of new phones, is 50% in the US. Most of these discards are coming from AT&T as Verizon has not carried the iPhone long enough for customers to begin replacing their handsets with a new model.
Dediu claims most of AT&T's reported activations were from customers replacing iPhones and that the carrier only added one million new iPhones thus far this year. He also points out that AT&T's discard rate has skyrocketed to 81% since Verizon introduced the iPhone 4 earlier this year, a figure that suggests AT&T is adding fewer new iPhone customers now that people have a choice in wireless carriers. It's an interesting look at the iPhone that goes beyond unit sales. You can read the full report at Asymco's website.