Last month X CEO Linda Yaccarino confirmed that video calls would be coming to the app formerly known as Twitter as part of its transition into an “everything app.” Now, new code in the X app reveals that both audio and video calls will be supported.

The new findings were uncovered by tech veteran-turned-investor Chris Messina inside the X app’s code.

Other lines of code refer to a warning that appears when someone tries to DM another user on the app which explains that “audio and video calls are a premium feature,” and entices them to “subscribe to gain access.” That means users will have to pay for X Premium, the subscription previously known as Twitter Blue, which includes a number of upgraded features including verification, a reduced ad load, the ability to edit posts, support for longer posts, prioritized rankings in search and conversations, and more.

To date, X has not been able to make a compelling case for X Premium, as independent research indicated that the company has only sold roughly 1 million subscriptions, according to researcher Travis Brown, who’s been tracking the success of the product over on GitHub.

For reference, X owner Elon Musk recently said the app has 550 million monthly active users.

X no longer responds to requests for comment after Musk’s takeover, only replying with an automated message to incoming press queries.

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