This is a confusing question and there is a simple answer.

You need a separate phone number for each videophone you have. This is so any incoming call will go to the right phone (this is true for devices made by ZVRS as they have the ZConnect feature). Devices distributed by other manufacturers depend on their configuration as well as the router configuration.

There could be 2 phone numbers assigned for each videophone you use by the videophone distributor. One is a local number and the other could be a 800 (866, 877 or 888) number. All videophone distributors are required to assign a local number to your videophone. The 800 number assignment is not required.

For 911 service, you need to decide which videophone you use for 911 service. You need to call the provider of that particular videophone to give them your local address information where you are located. This way, when you need 911 service, the operator will know where to send help to the address you provided. If you move your vidoephone or change your location, you should notify the videophone provider information about the change in location, otherwise the 911 responders could go to the wrong location.