This is most likely a really OLD person testing themselves just prior to crapping their fresh diaper, to see if they still remember how to dial a telephone number.  They quickly find out that on the first day of moving into the old folks home, they are automatically stripped of any and all skill that is required in order to perform this task.  But they always insist on trying to do it anyway, just so they can prove to themselves that they're no longer capable of doing it properly; They always dial the wrong number, and never reach the person they are trying to contact.  And THEN to top it off and to cover up the fact that they no longer possess this elementary skill, they decide that it is a FANTASTIC idea to simply hang up the phone, without leaving any message whatsoever.  This leaves the person that owns the phone number, dangling by his or her last nerve.  Why is their LAST nerve you might ask?  That answer is simple.  It's because they do this every damn day of the week!  They just don't remember doing it yesterday.  Damn it!!! Please STOP.