We are becoming less and less dependent on mobile networks. You can get a data signal almost everywhere that you can get a mobile signal and most of us are around WiFi most of the time anyway.

TCP/IPネットワークを介して、デジタル化された音声を送受信したり、呼び出し、切断したりする呼制御技術を含めた総称。 Facebookが、発信者番号通知、着信拒否、電話帳、VoIP通話機能を備えるAndroid向け通話アプリ「Hello」を米国でリリースした。（2015/4/23 ...

The apps are free to download from iTunes and Google Play and allow customers on MyNetFone¹s residential VoIP plans to make and receive low cost phone calls from their mobile device via Wi-Fi, 3G or ...