Signal’s claim to fame here is that they were subpoenaed in 2016 and could only supply account creation and last connection times:
> The American Civil Liberties Union announced Tuesday that Open Whisper Systems (OWS), the company behind popular encrypted messaging app Signal, was subpoenaed earlier this year by a federal grand jury in the Eastern District of Virginia to hand over a slew of information—"subscriber name, addresses, telephone numbers, email addresses, method of payment"—on two of its users.
> ... “The only information responsive to the subpoena held by OWS is the time of account creation and the date of the last connection to Signal servers,” Kaufman continued, also pointing out that the company did in fact hand over this data.
> The American Civil Liberties Union announced Tuesday that Open Whisper Systems (OWS), the company behind popular encrypted messaging app Signal, was subpoenaed earlier this year by a federal grand jury in the Eastern District of Virginia to hand over a slew of information—"subscriber name, addresses, telephone numbers, email addresses, method of payment"—on two of its users.
> ... “The only information responsive to the subpoena held by OWS is the time of account creation and the date of the last connection to Signal servers,” Kaufman continued, also pointing out that the company did in fact hand over this data.
https://arstechnica.com/tech-policy/2016/10/fbi-demands-sign...