Upgraded to iOS8 on both iPhone 5s and iPad Air. But no calls seemt o be working on iPad. It will attempt, but always says "call using iphone failed." They both have Bluetooth enabled, and HandOff is working fine, but no calling.
iPhone 5s, iOS 8
I rebooted both devices and it worked...
I had the same problem. But mine was resolved much more easily.
I logged out of iCloud,
on my macbook, under FaceTime - preferences
on my macbook, under Messages - preferences
on my iPhone, under Settings - Messages
on my iPhone, under Settings - Facetime
on my iPhone, under Settings - iCloud
Then resigned into all accounts.
call using iphone failed
