How Does VoIP Work?
If you’ve ever had a video chat on Facetime or Messenger, you’ve used VoIP. These communication platforms (and many others) rely on Voice over IP technology to transmit voice and video data over the internet.
Here’s a quick look at how VoIP works behind the scenes.
Packet Switching – The Basis of VoIP Technology
Voice over Internet Protocol technology (sometimes referred to as internet telephony) was originally developed to help users avoid long distance charges. The goal was to bypass the old telephone system completely, using the internet and a technology called “packet switching.”
Traditional telephone networks carry analog sound signals over copper lines via circuit switching. When one party calls another, a dedicated two-way connection or “circuit” is formed. The Public Switched Telephone Network (PSTN) makes all these connections possible.
Every circuit-switched call requires a continuous connection, from start to finish. The more ground a connection has to cover, the more costly it is to establish and maintain—especially when the endpoint is a country with older infrastructure. Hence, expensive long distance calls.
Instead of using copper lines and two-way circuits, VoIP phone systems use packet switching to transmit voice signals over the internet, like any other piece of data.
Information is divided and compressed into digital data packets that seek the fastest path across a network as circuits become available. With an IP header that tells it where to go (and how to reassemble once there), each packet is semi-autonomous and can travel separately from the rest.
Packet switching is the basis of online data sharing—and it’s also what gives VoIP systems their speed and clarity.
Making a VoIP Call (Behind the Scenes)
While VoIP is an internet-based technology, call recipients do need to be online. Your service provider can route data from your device’s IP address to any existing phone network.
There are a few different communication protocols a VoIP provider can use to facilitate these VoIP-to-any-other-phone connections. The most common is Session Initiation Protocol (often referred to as SIP trunking).
Here’s what happens what you make a VoIP call (in stages):
- You use your internet-connected smartphone, computer, laptop, tablet, or VoIP deskphone to dial a number.
- Your VoIP provider establishes the connection using SIP trunking (or another protocol).
- Your VoIP provider then transfers voice signals as digitized, compressed data packets from one user to another.
- The digital data reaches its destination (the receiving device) and reassembles itself into analog audio.
All this talk of packets and protocols may sound technical and complex (and it is), but the essential takeaway is VoIP technology uses the internet’s power to make voice calls more energy-efficient—and this means cost savings for you.