The Difference Between VoIP and PSTN Systems
Internet telephony isn't a new technology — it's been around for many years in one form or another, but only fairly recently has it become reliable and ubiquitous enough to be a serious choice for business. While Internet telephony was once an oddity often plagued for garbled and dropped calls, these days a well-planned and implemented VoIP system can provide call quality and reliability that rivals mobile phone or landline calls.
How VoIP Works
To understand how VoIP, short for Voice over Internet Protocol, works, it's helpful to compare it to how conventional phone calls operate. When you place a "regular" phone call using the Public Switched Telephone Network (PSTN), also known as Plain Old Telephone Service (POTS) you use what's called circuit-switched telephony. This system works by setting up a dedicated channel (or circuit) between two points for the duration of the call. These telephony systems are based on copper wires carrying analog voice data over the dedicated circuits.
This is in contrast to newer Internet telephony networks based on digital technologies. VoIP, in contrast to PSTN, uses what is called packet-switched telephony. Using this system, the voice information travels to its destination in countless individual network packets across the Internet. This type of communication presents special TCP/IP challenges because the Internet wasn't really designed for the kind of real-time communication a phone call represents.
Individual packets may — and almost always do — take different paths to the same place. It's not enough to simply get VoIP packets to their destination. Yhey must arrive through a fairly narrow time window and be assembled in the correct order to be intelligible to the recipient. VoIP employs encoding schemes and compression technology (see G.7xx for more information) to reduce the size of the voice packets so they can be transmitted more efficiently.
PSTN Versus VoIP: A Feature Comparison
DID YOU KNOW... How does one pronounce VoIP?
There are three popular ways to say it, with none being a definitive "right" way. All are correct.
To avoid the situation completely, if you're not comfortable using the term VoIP in a conversation, you can simply say.....
Parts of this article originally appeared on SmallBusinessComputing.com.
You can read the full version here in "VoIP: A Primer for Small Business".
|Key Terms To Understanding VoIP:
Related Articles on Webopedia:
This Webopedia study guide describes the different parts of a computer system and their relations. Read More »Webopedia Polls
The trend for the past two years has been for shoppers to spend more online during the holiday season. How do you typically shop for holiday... Read More »How to Create a Desktop Shortcut to a Website
This Webopedia guide will show you how to create a desktop shortcut to a website using Firefox, Chrome or Internet Explorer (IE). Read More »
- Watch Datamation's editor James Maguire moderate roundtable discussions with tech experts from companies such as Accenture, Dell, Blue Jeans Network, Microsoft and more »
Tape clearly is on the decline. But remember, legacy systems can hang for a shockingly long time. Read More »Apple Pay Promises to Strengthen Payment Security
Experts believe that Apple Pay and other competitive payment systems will be far more secure than cards, even cards equipped with EMV chips. Read More »Internet of Things Shaping IT's Future
To make the IoT both work and pay off, IT is juggling upgrading and building app-centric networks, mapping out new data center architectures and... Read More »