Comment by Yizahi

In ex-USSR SMS are dead, except on old "feature" phones. While in capitals a lot of people have iPhones it's share is not more than 50% and so iMessage never really picked up. Currently messaging it split between Viber (mostly older people) and Telegram (mostly younger people), plus some FB Messenger with FB friends. Whatsapp lost out market when it cost 1$ to install (yes, for many it was a decisive factor). iPhone users just install these apps too.

When traveling in Europe I usually see Whatsapp as a contact method.