How Does VOIP Work?

VOIP, also known as Voice Over Internet Protocol, allows users to talk over their computers just like they were making a regular phone call. Audio signals are collected, turned into digital signals, and then transmitted over the Internet.

Not only is making a VOIP call fun, it also doesn’t carry with it the charges of a cell phone or land line. If all your friends have a computer and compatible software, you can essentially make free telephone calls (even to the other side of the planet).

This will have a major effect on the way calls are made in the future, and it‘s not outrageous to assume that VOIP calling may one day be the industry norm. The FCC is currently taking a close look at VOIP technology, and phone companies such as Vonage and AT&T are starting to get in on the action by setting up calling plans.

Three Types of VOIP Calls

So how does VOIP work? To fully answer that question, we need to examine the three ways in which a VOIP call can be placed.

  • IP Phones – The IP phone looks much like a standard phone; it has buttons, a handset, and even a cradle. The difference is in its connectors, as it uses a RJ-45 Ethernet connector instead of the standard RJ-11 phone connector. The IP phone is hooked to the router on your computer. If you have a wireless connection, you can even purchase a Wi-Fi version of the phone which will allow you to make calls from any wireless “hot spot.”
  • Computer to Computer – This type of VOIP has numerous free and reasonably priced software available. By calling from computer to computer, you eliminate long distance charges.

Besides the required software, you’ll also need the following to make a computer-to-computer call: microphone, speakers, sound card, high speed Internet connection. The better the quality of these items, the better the quality of your phone call will be.

Keep in mind that the person on the other computer must have software which is compatible with your own. If it’s not, then you’ll be unable to place a computer-to-computer call. This shouldn’t be a problem, however, as free software is available online and can be set up in under 10 minutes.

  • ATA – The ATA is also known as an Analog Telephone Adaptor. A simple device, the ATA allows you to connect a regular telephone to your computer for the purpose of making calls. The analog signal from the phone is converted by the ATA into a digital signal and then transmitted.

The Mechanics of VOIP


If you’re still wondering, “How does VOIP work?”, then this section should answer any remaining questions that you might have. Afterwards, you’ll be ready to get your own VOIP system and make some free Internet phone calls.

Once two computers have installed compatible software, they will be able to make computer-to-computer calls. This is accomplished by speaking into the microphone (or telephone receiver) and allowing your analog signal (voice) to be converted to a digital signal.

In order to keep these digital voice signals from taking up too much bandwidth, your computer will compress them. The method of compression is known as CODEC. This compression improves the quality of transmitted voices, but it also eliminates sounds outside the range of human speech (which would greatly increase bandwidth requirements).

When the voice has been compressed, it is placed into data packets and sent across the IP network. A standard IP packet contains anywhere from 10 to 30 milliseconds of audio. This process has come to be known as “packetization.”

If a packet doesn’t reach its destination, the system has the ability to fill in the gaps and reconstruct the missing signal based on the packets received before and after. With the current growth of technology, most VOIP conversations are now as reliable as speaking directly over a telephone line.