This works via DAB (radio) and this is possible in many countries. The navigation system must be connected to the cigarette lighter with the original cable (acts as an antenna). However, I have noticed that the information is often not correct or accurate and I usually leave it switched off.

DAB, yes, but I don't even get reliable messages in Switzerland. With DAB, I often get delays on my journeys where there are none at all. If I then switch on Bluetooth so that the navigation system connects to the mobile phone, the delays suddenly disappear with the live connection, which usually corresponds to the facts. DAB doesn't exactly make a trustworthy impression, and whether it works better abroad? I play it safe and for the holiday season I usually buy a roaming data package (Aldi Mobile), which doesn't cost the earth and for these few K of data traffic, roaming can safely remain switched on during the journey.