It said 1/4 of their current smartphone user base. That isn't so far fetched.
Weren't there surveys from ChangeWave a few months back that showed a 1/3 of Android owners were planning to buy an iPhone next and 1/4 of Verizon customers strongly interested in a Verizon iPhone? That would support the claim that a 1/4 of their current smart phone users are going to the iPhone.