A text message addressed to someone else comes into your cell phone.  It looks urgent – “a rescheduled meeting, an illness or a a romantic get together.  

Nice people response back “Sorry, wrong number”.  The scammer (usually an automated chatbot) – keeps up the friendly messages and will invite you to fake site, so the user can hand over their credit card information and money.  Don’t forget the scammers primary aim is to identify valid phone numbers that the users are willing to engage.