It looks like voice and video calls are coming to the browser version of WhatsApp. WABetaInfo reported the presence of new call buttons on the web client, indicating that the calling features will be accessible on all versions of WhatsApp in a future update.
Currently, users who want to make voice and video calls on desktop need to download and install the app, as the browser version of WhatsApp only allows users to send messages and media. Worth noting that the button for video calls is already there, but it’s greyed out and hitting it will prompt you to download the app instead. The addition of calls to WhatsApp Web adds a layer of convenience for users as they can simply make calls directly from their browsers, be it Chrome, Edge, Safari, or any other compatible browser.

Additionally, implementing voice and video calls in the web client will give users a more consistent and unified experience when using WhatsApp, as the browser version will become more like its mobile and desktop app counterparts. It will also give the app more versatility, as users can stay connected regardless of their choice of platform or device. There will be no need for users to switch between devices when they want to make calls.
For now, there are no details on the specifics and limitations of this feature for WhatsApp Web. However, it is likely that voice and video calls will work the same way as in the mobile apps, with a simple interface for making and receiving calls, as well as managing conversations. It is also uncertain when the feature will be available for users as it is currently still in development.
(Source: WABetaInfo)