phone calls from the dead

many years ago I remember reading a book called "phone calls from the dead" this was pre the digi age,apparently there were many cases on record of people answering their phone ,only to find themselves talking to a decesed relative or friend,the bizarre thing was ,when they were talking to the caller they seemed to forget that the person was dead,only afterwards did the full import of it register,most voices seemed perfectly normal,but in other cases the it was stated that the voice seemed to have a metallic sound to it ,dalek like,in one particular case there even seems to have been what you might call,a spirit telephone operator,directing the call,all very strange,but there are loads of cases like this in the book