There are, however, disadvantages to the VoIP technology.
Traditional analogue phone lines work even when power is cut. They receive their power from the phone lines. VoIP, however, only uses power from the in-house source, i.e. your own source of power. VoIP will not work without a power supply.
Calls made to emergency services usually get re-directed to a local emergency call centre. Due to the nature of not being able to geographically locate the VoIP systems, calls can be lost or disconnected when contacting the emergency services.
VoIP service providers may or may not choose to offer directory listings. This can, however, be set up manually by the VoIP user.