I can't answer this kooky phone half the time, It's ringing ringing ringing, I'm pressing the green button, phone still ringing. Stops eventually but sheesh, sure hope it's not important.
In my case Belo, yes I've tried swiping. Sometimes I'm able to answer it, seems to happen when it's not in use. Ready to ditch this 'thing' & get another Samsung Galaxy. Not a fan of this phone
Different phones work in different ways - tap, slide left, slide right, slide up - experiment. Phone calls are usually free (some countries still charge by the call - and Lifeline accounts have limited minutes, otherwise experiment all you like).