To receive Google Map API Key, go to your Google account first.
Go to This Link and as the image below, select GET A KEY.
If you don’t have a Google account, start form here: https://www.wikihow.com/Make-a-Google-Account
A pop-up window will open and in input form you can select your project or create a new project to get Google API Key. Set your project or site name and click on Create And Enable API.
After you enabled, you will receive API, copy that and put it in WordPress – Admin Dashboard > VOIPhone Options > General > General Tab.
Now go to this link: This Link and select your project and click on continue to enable API.