> During the window when an attacker had access to Twilio’s customer support systems it was possible for them to attempt to register the phone numbers they accessed to another device using the SMS verification code. The attacker no longer has this access, and the attack has been shut down by Twilio.
It also seems like there is also a buffer period when the numbers are registered and not yet purged from the twilio system:
> 1) their phone numbers were potentially revealed as being registered to a Signal account, or 2) the SMS verification code used to register with Signal was revealed.
We don't know how often Signal purges that, so, although unlikely, it could be a day or a week or more of registrations.
Here's an article from last year mentioning 50M+ downloads in 10 days. https://webcache.googleusercontent.com/search?q=cache:hsVnnQ...
That was a period in which WhatsApp had just announced their new ToS, indicating that the data about their users was to be merged with Facebook's. Consequently, many users became aware of the enormous privacy issues with all Facebook/Meta products, and abandoned WhatsApp for other services, mostly Signal and Telegram.
I doubt that this period can be used to interpolate the Signal growth for the rest of the year, although the network effect has probably resulted in a much higher growth rate than before the WhatsApp exodus.
Edit: a Tweet from Elon Musk ("use Signal") most probably contributed a lot to that raise in awareness, and the one-time surge of increased growth for Signal.
I've registered dozens of devices, since the account pairing expires after five minutes (ok, slight exaggeration).