Does T-Mobile owe BlackBerry anything?

T-Mobile targeted BlackBerry uses with an email offer urging them to swap to Apple's iPhone. The ensuing hubbub, outlined in a blog post from BlackBerry CEO John Chen, raises a key question: How much loyalty do wireless carriers owe smartphone makers?

To be sure, T-Mobile wasn't the ideal partner since it launched its campaign, kicked BlackBerry while it was down and never gave the company a heads up.

Chen thanked customers and said:

To T-Mobile, I would like to remind you that our long-standing partnership was once productive and profitable for both BlackBerry and T-Mobile. I hope we can find a way forward that allows us to serve our shared customers once again. Notwithstanding the current challenge, we remain very excited about BlackBerry’s future.

The big question: What does T-Mobile owe BlackBerry? Customers have gone to other devices in many cases and T-Mobile would obviously like to retain those folks on its network should they switch phones.

BlackBerry and T-Mobile along with other carriers have been strong partners for years, but if the devices aren't selling perhaps loyalty only goes so far. Instead of bemoaning the situation and rallying mock outrage, BlackBerry's time may be better spent creating a kick-ass device that brings customers back. And then BlackBerry should give that device to every carrier but T-Mobile.