An Alarm/Entry System can be specified using Closed Circuit Television (CCTV) or Speakerphones so the householder can control those legitimately wishing to gain access to the home.
This can be combined with remote door opening. An Entry Phone or Videophone means you can hear or see for who is there. Entry codes, card readers or key pads enable regular visitors to have unrestricted access, whilst requiring unexpected visitors to reveal their identity.