The German Zollkriminalamt monitors WhatsApp, Signal and Telegram by discreetly linking a device to the target’s account – much like WhatsApp Web – without using spyware
To establish the link without the target’s knowledge, investigators use ruses such as fake summonses, phishing or the interception of Telegram verification text messages
On 20 January, the German Federal Court of Justice ruled that only messages sent after the judge’s order are admissible, rendering previous exchanges inadmissible in a doping case
translated from the german link:
If you don't need your phone when you travel: burner. If you do need it: switch it off. If you visit the popo, leave your phone at home.