If someone calls me using Facetime using their cellular service (not wifi) & I answer the call in my home where I have wifi & cellular will the call connect via wifi or would it be on my cellular service. Wondering if I would be using data.
If you're connected to wifi then it will use wifi.
If you're not connected to wifi it will use cellular data.
Just like with everything else that needs data.
As Applejuiced said, if you're connected to your home network then the Facetime data will be used from your broadband allowance, not your cellular allowance.