Yesterday after HDD crash, I needed to reinstall my Yosemite.
So after reinstalling, checked 10.10.1 update (in app store, no ComboUpdate).
I have an Asus Commando motherboard with no WiFi/Bluetooth or adapters.
Due to that, in my iPhone 5 (Jailbreaked) I haven't checked the 'handoff' option for obvious reasons.
My surprise was when my friend called me and I get on my Mac the notification (using FaceTime app) of the call.
I can receive it and can speak and listen only with the OS X. Checked again with the iPhone turned on and nobody happens, so checked that only works when the iPhone is on standby mode.
I haven't checked well Handoff, but Option on Prefs -> General isn't avaiable.
So I can confirm Continuity (calls) works perfectly if you have your FaceTime/iMessage account working on your OS X and your iPhone is on the same network of your OS X (even with OS X over Ethernet only, that is my case).
Please feedback to know why. I can report what is needed. Greetings!
EDIT: Handoff doesn't work. I can use Contacts and call (via FaceTime) a mobile phone perfectly. Sounds works great. Only use WiFi on iPhone 5 and Ethernet on OS X.
EDIT 2: Resolved. Only it's a FaceTime option that let use iPhone for call-receive in OS X without bt/wifi on OS X. iMessage not login but FaceTime login perfectly.