I have a mid-2013 Macbook Air running Yosemite and a iPhone 5s with iOS 8. Unfortunately I can't make calls from my Mac using Handoff. I can receive calls but when I try to call from my Mac using my iPhone there is a message saying ''Call failed'' or ''iPhone not available'' though my Mac and iPhone are on the same WiFi network, are both logged in with the same Apple ID (in iCloud and FaceTime), all the Handoff settings are turned on and Bluetooth is on on both devices. Anybody knows how to fix this problem?