"In a few months, I will discontinue my phone number and only use X for texts and audio/video calls," Elon Musk wrote on X early Friday morning. The post was viewed 16 million times as of 0820 ET. 

Musk has repeatedly said he will transform X into an "everything app. "

This includes one of the newest features, released in late 2023, to make audio and video phone calls. 

X CEO Linda Yaccarino has posted about making video calls. 

X's feature to make calls is exclusive to Premium subscribers. Nonetheless, these subscribers (charged $8 per month) can call any user on X, provided the user has previously sent them at least one direct message.

If Musk gives up his phone number, a major question remains on how the billionaire will deal with the two-factor authentication that some apps and services require. 

Here's how X users responded to Musk's post:

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Musk teased days ago about the 'everything app.' 

Hmm... 

The everything app is taking shape.