When flip phones gave way to Smart phones, we asked, "What's next?" Now that the phone has become a 'device', the actual use of this unit is for data access and not so much as a 'telephone'. Making calls has fallen for many users to the point where voice calls and text messages are just another app, and no longer the primary use of the phone...er device.
This has led to cheaper, 'data-only' plans, and your phone number is no longer the domain of your wireless carrier. I was hit with this reality while roaming in Europe where I only needed a SIM for data access, not a plan that enabled calls to the US or locally. All you need is a data SIM. You bypass the need for identification and you make whatever calls you want with an app...for free, and only if you want...you don't lose any prepaid minutes. This has been the basis for "Wi-fi Calling" but just as easy on any data-connected device.
In our case, we used Google Hangouts (and the Hangouts Dialer) for outgoing calls, and Google Voice and Hangouts for incoming calls. If configured properly, your Google Voice number shows on Caller ID. You know what, this sounds complicated. But after you use it, you begin to realize this is revolutionary...and just as usable at home as it is for roaming. At worse, your outgoing calls show a Caller ID of "unknown number", because your call has no number. Because a number we no longer need. Us cheapskates are cheering.