A fake 'BT' person phoned my elderly mother about a problem with her internet which was affecting "everybody in her sheltered housing", they wanted her to go to a web link and click on it to install some software which would fix the problem for her 
She's not a BT customer but thought they were calling because BT provide the phone lines. Fortunately she told them she wasn't going to click the link until she'd spoken to "her IT expert" (me!)