Elon Musk announced Thursday that Starlink Mobile is close to offering nationwide phone coverage in the U.S. after securing tools that will help signals penetrate through walls and other obstructions.

Musk shared an X post from Sawyer Merritt, a prominent Tesla investor and commentator, who wrote: "AT&T CEO: Starlink Mobile won't be able to penetrate walls. SpaceX: We've acquired 800 MHz spectrum, which will allow Starlink Mobile to provide better indoor coverage, including signals that can penetrate walls and other obstacles. People are underestimating Starlink Mobile."

Musk noted that "this is the last critical piece of the spectrum puzzle needed for SpaceX to provide complete phone coverage in America."

A Friday report from CBS News said that SpaceX agreed to buy licenses for radio airwaves that will help the Starlink Mobile satellite business offer cell service inside of buildings, allowing it to compete with other major carriers.

The agreement still requires approval from the Federal Communications Commission, but if it's allowed to move forward, it would permit Starlink to combine its satellite-to-mobile transmissions with "an advanced terrestrial deployment that can seamlessly connect devices everywhere," a company statement read.

SpaceX did, however, add that the FCC has approved Starlink Mobile's application to launch 15,000 satellites to transmit radio waves in the 2 gigahertz band and connect directly to cell phones.

"These airwaves are compatible with existing handsets, and we do not foresee obstacles to regulatory approval," UBS analyst John Hodulik told investors.

"That said, we still believe it will take time for SpaceX to scale its wireless ambitions, and the impact to near-term wireless industry fundamentals is limited."

This news comes as a new documentary entitled "Musk" is set to open in Los Angeles and New York theaters on Friday.

The film, said to be critical of the world's first trillionaire, included clips of his own employees saying negative things about him and his companies, NBC News reported.

Musk already slammed the four-hour film as a "hit piece" that is "boring," and went after director Alex Gibney, according to Variety.

Musk said that Gibney had "just assembled a hit list of people who either have an axe to grind or don't even know me (but still have an axe to grind)."