Voice over IP (VoIP) is a method to carry telephone calls over the data networks and Internet. VoIP converts the analog signals of voices into digital information that is transported in IP packets. VoIP can also use an existing IP network to provide access to the public switched telephone network (PSTN).
VoIP phones look like normal phones, but instead of using the standard RJ-11 phone connector, they use an RJ-45 Ethernet connector. VoIP phones connect directly to a network and have all the hardware and software necessary to handle the IP communications.
When using VoIP to connect to the PSTN, you might be dependent on an Internet connection. This can be a disadvantage if the Internet connection experiences an interruption in service. When a service interruption occurs, the user cannot make phone calls.
There are several ways to use VoIP:
- IP phone - A device that connects to an IP network using an RJ-45 Ethernet connector or a wireless connection.
- Analog Telephone Adapter (ATA) - A device that connects standard analog devices, such as telephones, facsimile machines, or answering machines, to an IP network.
- IP phone software - This application connects by using a microphone, speakers, and a sound card to emulate the IP phone functionality.