So many people are joining Signal that there's now a wait.

The end-to-end encrypted messaging app endorsed by the likes of Edward Snowden got a major (ahem) signal boost Thursday when Elon Musk tweeted his support. Soon after, Signal announced that the tidal wave of new downloads was having an unintended effect.

"Verification codes are currently delayed across several providers because so many new people are trying to join Signal right now (we can barely register our excitement)," wrote the nonprofit. "We are working with carriers to resolve this as quickly as possible. Hang in there."

When registering new Signal accounts, users must provide phone numbers. Verification codes are then sent to those phone numbers, thus confirming the numbers are indeed controlled by the people claiming to control them. It is this process that is apparently backed up due to a spike in registration attempts.

Prime Day deals you can shop right now

• iRobot Roomba Essential Vac Q011 Robot Vacuum Cleaner—$159.99(List Price $249.99)

• Samsung Galaxy Tab A9+ 10.9" 64GB Wi-Fi Tablet—$142.49(List Price $219.99)

• Apple AirPods Pro 2nd Gen With MagSafe USB-C Charging Case—$168.99(List Price $249.00)

• Fitbit Charge 6 Fitness Tracker With 6-Months Membership—$99.95(List Price $159.95)

• Apple Watch Series 9 (GPS, 41mm, Midnight, S/M, Sports Band)—$279.99(List Price $399.00)

All this following a two-word tweet from Musk: "Use Signal."

Tweet may have been deleted

Of course, Musk's Thursday endorsement doesn't come out of nowhere. It follows on the news that WhatsApp — a Facebook-owned messaging app — is updating its privacy policy on February 8. That new policy will force new users to share their data with Facebook.

Tweet may have been deleted

As PC Mag reports, if an existing WhatsApp user previously opted out of sharing that data (an option buried deep in the settings) Facebook will continue to honor that opt out — at least for now.

While Musk didn't cite this change specifically in his tweet, the timing suggests it's not a coincidence. The Tesla CEO's opinions on the social media giant are well known.

"Facebook sucks," he wrote in May of this year.

Tweet may have been deleted

"Just don’t like Facebook," he wrote in March of 2018. "Gives me the willies."

Tweet may have been deleted

Signal likewise saw a bump in downloads earlier this year amidst nationwide Black Lives Matter protests and fear of police surveillance.

SEE ALSO: The best messaging apps not owned by Facebook

As of the time of this writing, Signal is ranked 20th in the App Store's "Social Networking" category. WhatsApp is ranked third.

UPDATE: Jan. 7, 2021, 12:49 p.m. PST: According to Signal, those verifications codes should be flowing freely once again.

"Everyone should be able to register without delay again," it announced. "Thanks to all of the carriers who flipped the right switches so that people can keep switching."