et. However, IP-based calls can be made without involving the Internet at all. For example, a corporation may interconnect multiple locations using dedicated private line facilities, and they may transport IP-based phone calls across that dedicated network facility. This is clearly VoIP, but is not Internet telephony. There's a big difference. VoIP Evolution There was a time when VoIP was only for the brave: those intrepid explorers among us who were willing to try Internet-based telephony just to prove that it could be done, with little regard for QoS, enhanced services, and the like. In many ways it was reminiscent of the 70s, when we all drove around in our cars and talked to each other on CB radios (Remember? Oh, come on "10-4, Rubber Duck. See you on the flip side." Don't deny it ). The quality was about that good, and it was experimental, and new, and somewhat exciting. It faded in and out of the public's awareness, but didn't really catch on in a big way until late 2002 or so, when the level of broadband penetration reached a point where adequate access bandwidth was available, and CODEC technology far enough advanced to make VoIP not only possible but actually quite good. Everyone toyed with the technology; Cisco, Avaya, Lucent, and Nortel, Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com Copyright © 2004 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Telephony Chapter 3 not to mention Ericsson and Siemens, all built VoIP products to one degree or another, because they knew that sooner or later the technology would become mainstream. But as always happens, it took early intro- ducers (not early adopters) to make the transition from experiment to service. And while companies like Telus in Canada played enormous roles in the ongoing development of VoIP (they were the first company to install a system-wide IP backbone, and one of the first innovators to offer true VoIP services), it took a couple of s