The "Encrochat" was also a phone for criminals but that went to shit. Loads of crims in The UK have been jailed when The French got access to the servers!

I'm 3/4 way through the book 'dark wire'. That's a good read too.

+ if u want more on encro chat there's a 6 part BBC sounds thing on it, think its called 'catching the kingpins'.. Its OK ish considering its a BBC thing. ;)