An old scam from years ago was carried out when a smartly dressed female often with small child would knock on the door and explain that her car had broken down and her mobile phone battery was dead, if you would let her phone her mechanic husband who was at home, he would come out and rescue her.I seem to remember once (or I may have completely made this up)
Someone changed their number to a premium rate one so when he got cold calls it cost them a fortune to ring him
If you let her use your phone she would make the three or four minute call very convincingly and explain to her husband where she was etc. She'd thank you very much and leave.
Much later when you got your phone bill you found that the number she'd dialled was a £50/minute number.