We finally found the solution for this problema between iOS 8 and Yosemite. When you try to make a call from you Mac using your iPhone you hear a strange sound.
How to solve that?
1. Try to make a pone call (if you have a weird background sound)
2. Connect your iPhone with the USB to your Mac
3. Trust your device
4. Try again to make a phone call (this time without sound)
Thanks for following,
Contact us: firstname.lastname@example.org