BRIMAC41-

As a consumer myself, I certainly understand the importance of using WIFI calling especially since it is included with your plan. A "Bring Your Own Device" can certainly work in our network as long as it is unlocked; however, we don't have control over the availability of the features we provide that are not available from your unlocked phone. The reason why is that it is a software that your phone should have if the phone was manufactured for Verizon. While we can activate your non Verizon unlocked phone, unfortunately, some features like WIFI calling may not work up to our network. The best way to prevent this from happening is to acquire a Verizon device to ensure it has all the necessary software that it needs to work with the features that we offer. Please know that we can't modify your phone's software as this is done by the manufacturer. We provide you the service and can guarantee the full functionality of the phone as long as it is a Verizon device. 

At this time, we don't have information on the Moto X4, so I apologize for the inconvenience. You may sign up for email alerts about our latest products and services at https://vz.to/1m2tKLh

CarmenT_VZW
Follow us on TWITTER @VZWSupport
If my response answered your question please click the _Correct Answer_ button under my response. This ensures others can benefit from our conversation. Thanks in advance for your help with this!!