The feature is simply known as Calls. In addition to answering calls, the feature also allows you to make them from your PC. You can also decline them and send them to your phone’s voicemail, as well as access its recent call history. It’s also possible to transfer them seamlessly between the phone and PC.
To make use of Calls, you’ll need a phone running Android 7 Nougat or higher. Your PC, on the other hand, needs to have a Bluetooth radio. A known issue with the feature for now is that it sometimes needs you to unpair and pair your devices to use it. Microsoft says that the Calls feature will gradually roll out to other Windows Insiders running build 18362.356 (19H1) and newer. As for when it will officially roll out, the company has not disclosed information on that just yet. (Source: Microsoft via CNET)