Cell phone scam?

My elderly friend was approached twice and I was approached once by the same young man asking to borrow our cell phones.  The story was always the same:  his girlfriend and baby were in the car and they had run out of gas, had no money and he needed to make a phone call. We both felt suspicious of his story, especially since it  happened three times within 10 days!  Once in Edgewood Towne Center Giant Eagle, once in Staples on Penn Avenue and once in Panera Bread in Monroeville (near the Talbot's outlet).  I googled cell phone scam and learned that people can do something with your phone in a few short minutes that allows them to make charges to your phone account.  A word of caution.