Apple Reports First Quarter Results
http://www.apple.com/pr/library/2012/01/24Apple-Reports-First-Quarter-Results.html
Information highlights:
The Company sold 37.04 million iPhones in the quarter.
International sales accounted for 58 percent of the quarter’s revenue.

Let start with the guess work:
1. Assume total domestic iPhone sales are 42% of total iPhone sales:
Total domestic iPhone sales = 0.42×37.04M = 15.56M
2. AT&T sold 7.6M
3. Verizon 4.2M

Therefore, Sprint and the other US carriers sold:
15.55M-11.8M = 3.75M

Since Sprint is the only major carrier other than AT&T and Verizon,
we can safely assume:
Sprint sold 3.75Mx0.75 = 2.81M
Minus or plus 0.5M

Therefore, Sprint should activate about 2.8M-3.0M iPhones in December quarter of 2011.

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