I've never had trouble pairing - the issue I have is only with outgoing calls being routed through the car.
In other news, iOS 8.1.2 dropped today. The release notes say they've fix a problem with purchased ringtones disappearing (the horror!) while I continue to take my life in my hands every time I need to make a phone call from the car. As expected, iOS 8.1.2 did not address this bluetooth issue. Nice job on the bug fix priorities there Apple... I've also done further testing and found that the problem is not limited to Mazda - my 2013 Honda has the exact same problem. The phone pairs normally, music works normally, incoming calls work normally. Outgoing calls cannot be routed to the car until after the other end has answered, at which time the call must be manually routed to the car. This happens on my iPhone 6 and iPhone 5, both running every iteration of iOS 8.x there has ever been. The only common thread is iOS 8.