that is an old school and simple method of getting access into someone's phone line in order to use it for multiple things...NONE GOOD.Pk does anyone know if someone calls you and you try to answer there is a recording on the phone. The person sends you a text and says call me back. Does that get them into your phone so that they can make calls?
And in regards to your other post. There will always be scammers, just that these ppl choose the most harshest of ways to get their end goal
AVOID ANYONE LIKE THEM JUST AS YOU WOULD AN STD OR OTHER VENERIAL DISEASE