T-Mobile incurred the wrath of BlackBerry CEO John Chen and some of the phone’s loyalists by making an upgrade offer encouraging BlackBerry owners to trade in for a new iPhone. Aiming to make amends — and really calling the BlackBerry bluff — T-Mobile launched an upgrade offer that gave BlackBerry owners the choice of sticking with that platform or moving to another smartphone. T-Mobile’s BlackBerry trade-in promotion did indeed drive lots of people to upgrade — just not to new BlackBerrys. According to a field sales memo obtained by TmoNews, the promotion, which is ending on Wednesday, led to a 15x increase in BlackBerry trade-ins. But the most interesting number is how many went for something other than a new BlackBerry. Even with an extra $50 offered to those who chose a Q10 or Z10, 94 percent of the people taking part in the promotion opted to switch smartphone platforms.