Can be unsettling @whispersystems: I creeped out @hollowaynz because i had his number and he didn't have mine so i knew when he installed ithttps://twitter.com/tveastman/status/845920870715441152 …
Notifications aren't being transmitted, it's all happening local to the device. See for more on rationalehttps://www.jwz.org/blog/2017/03/signal-leaks-your-phone-number-to-everyone-in-your-contacts/#comment-172746 …