At #37c3 they have IRC, and Matrix for text and for voice they setup their own LTE/2G/3G/SIP/DECT network where you bring whatever phone-like device and pick a 4 digit phone number.

Meanwhile in the USA for #defcon they just paid Discord money and told everyone to accept their privacy policy, and even the DC Privacy Village asks people to sign up for Slack and Google.

People ask why I fly to CCC from the USA. It is because that is the closest place to find a thriving hacker culture.