Comment by jeroenhd

Even within the Netherlands there are pockets of Signal users, Telegram users, and in rare occasions even people using SMS or iMessage. Facebook Messenger also has a foothold in some circles.

That said, you'd be an outlier if you have a mobile phone but no WhatsApp. Everyone has WhatsApp, but fortunately not everyone is using it for everything. Unfortunately, that usually means using an even less secure and trustworthy messenger service.