In our first installment of VoIP Basics, we took a look at “What is VoIP?” Today we will explore the nuts and bolts behind VoIP calling to gain a better understanding of “How VoIP Works”. In case you missed it, click here to read the first installment, “What is VoIP?“
How Does VoIP Work?
Voice over IP works in a different manner then the traditional Plain Old Telephone Service (POTS) we have been using for the past few decades. Rather then leverage the circuit switch system like POTS, VoIP utilizes packet switching. As we discussed previously, IP is a data-oriented protocol used for communicating data across a packet-switched network. The specific steps involved with a VoIP call might vary based on what type of VoIP calling you are utilizing, but in general all types of VoIP calling follow this general process.
- Your analog “voice stream” (you talking) is broken down into digital packets (by hardware, software, or both, depending on the type of VoIP call). These digital packets contain the information of the call, such as sender/receipient ip address and the actual data.
- The digital packets are then compressed using a VoIP codec (e.g. G.729, G.711). The compression rate of the codec used by the VoIP Service provider influences the overall call quality, but the larger the packet the greater the risk for a decrease in quality of service due to network bandwith limitations (too many simultaneous calls on the network).
- The compressed digital packets are then sent off to their end destination. With the old circuit switched system when a call was initiated a “permanent” route was established for the duration of the call. With the packet switched system, the compressed digital packets follow the “path of least resistence” to their final destination.
At the recipient, the compressed digital packets are reassembled, decompressed, and converted back to “voice streams” by hardware, software, or both depending on what type of set-up the call recipient is utilizing.
- This is another factor in the overall Quality of Service (QOS) of VoIP. Because most calls do not have permanent route, network congestion could cause the loss of some packets which results in the loss of parts of your words and conversation.
In Laymans Terms: VoIP works by utilizing hardware and software to turn your voice into individual packets that are sent over an IP network (including the Internet) to the person on the other end of the call. Prior to the person on the other end of the call hearing your voice, the individual packets are put back together and converted back to your voice.
Up next we will take a look at the different types of hardware and software that can be used to make a VoIP call.