For example, say our numbers end in "00" and "01." If someone is calling the "00" number, the call is being received by both the "00" and "01" lines. It is not a call-forwarding issue as I have checked and that function is disabled on both lines. Thanks in advance for any advice.
We have the same problem. Did you get it resolved? We have a family plan and we're sure the call-forwarding is disabled on both phones (confirmed by the website) and *73.
How can we fix this behavior (calls to any of our phones ring simultaneously on our phones)? It started recently.
Are you using the same Apple ID for each phone? Each line should have it's own Apple ID.
Go into Settings, then Facetime and turn off the iPhone Cellular Calls on each device.
You probably have the same iTunes account and the setting above forwards calls to all devices signed into the same iTunes account. It actually is using the same technology as Facetime, which is why it is in the Facetime settings.