What is Voice over IP?

Voice over Internet Protocol, also called VoIP, is the routing of voice conversations over the Internet or through any other IP-based network.

Protocols used to carry voice signals over the IP network are commonly referred to as Voice over IP or VoIP protocols. They may be viewed as commercial realizations of the experimental Network Voice Protocol (1973) invented for the ARPANET.

Voice over IP traffic can be deployed on any IP network, including ones lacking a connection to the rest of the Internet, for instance on a local area network.

In general, phone service via VoIP is free or costs less than equivalent service from traditional sources but similar to alternative PSTN (Public Switched Telephone Network) service providers. Some cost savings are due to using a single network to carry voice and data, especially where users have existing under-utilized network capacity they can use for VoIP at no additional cost. VoIP to VoIP phone calls on any provider are typically free, whilst VoIP to PSTN calls generally costs the VoIP user.

There are two types of PSTN to VoIP services: DID and access numbers. DID will connect the caller directly to the VoIP user while access numbers requires the caller to input the extension number of the VoIP user. Access numbers are usually charged as a local call to the caller and free to the VoIP user while DID usually has a monthly fee. There are also DID that are free to the VoIP user but is chargeable to the caller.

VoIP allows users to travel anywhere in the world and still make and receive phone calls.