If you hadn't heard, BlackBerry chief John Chen isn't happy with T-Mobile -- he believes the carrier fired a shot across the bow when it enticed BlackBerry users to switch phones in a recent promotion. To mend that bruised relationship, the magenta network is launching a limited-time trade-in offer that gives loyal users a strong incentive to upgrade. As of February 21st, T-Mobile will give you $200 for your existing BlackBerry, and $250 if you're upgrading from a T-Mobile BlackBerry to a BB10 device like the Q10 or Z10. The payout is the same regardless of the device's age, so long as it's in good condition; if you're still rocking a Curve 3G, you'll get the full amount. Market share trends suggest that there won't be too many people upgrading to new BlackBerrys, but the olive branch is welcome all the same.