Yes. It will work. Make sure each device has a unique valid e mail address associated with it. You can add additional ' receive at addresses' in the face time settings.
Both devices will need face time enabled, and both will need to be on a wifi network. If your phone and pad are currently sharing an e mail addrss, if you call it, ft will be confused. So get a second e mail address for the pad.
The phone is probably fine without a second addrss, as it has a number which is u ique to it.
When you call the phone from the pad, select the number, as opposed to the e mail address. When you call the pad from the phone, select the new, unique e mail address.
Note, you can get a second e mail address from almost anywhere. G mail is a good choice. When you add the address to the FaceTime screen it will want to verify that the address is valid. Will send a e mail to that new addrss, and it will not work until you respond to that e mail.