where i live (western europe), the telco's overcharged for sms, making a decent conversation costs euros each. Whatsapp + wifi is free.

I heard that originally sms wasn't meant to be a consumer product, it was just so technicians could test or communicate. Then the telco's realized people like texting more than calling (people prefer async sometimes, weird because comms mainly developed from async to sync), and decided to charge a limb for it.