PDF of this tutorialSupport for voice communications using IP, which is usually called VoIP, has become especially attractive to consumers given the low-cost, flat-rate pricing of the public Internet.
VoIP is the ability to make telephone calls and access service over IP–based data networks with a suitable QoS and superior cost/benefit to PSTN–based calls. Today, most of the VoIP implementations are carried over ATM–based transport as shown in the second column of Figure 2.
The benefits of implementing VoIP are mostly consumer-based and can be divided into the following three categories:
- Cost reduction—IP is everywhere. It is on our desktops and it is what the Internet is based on. Many people view the Internet as a "free transport" for data and voice services. With the introduction of Net2Phone and other similar "free" services, many people are now making phone calls over the Internet. In addition, businesses and individuals have turned to higher-quality commercial products and services to make voice calls based on IP. The prevalence of IP nodes and the abundant supply of better IP–based switches and routers continue to reduce the cost of providing VoIP.
- Simplification and consolidation—An integrated infrastructure that supports all forms of communication could allow more standardization and could reduce the total equipment complement. The differences between the traffic patterns of voice and data offer further opportunities for significant efficiency improvements. Universal use of IP for all applications, voice and data, holds out the promise of both reduced complexity and more flexibility.
- Advanced applications—Even though basic telephony and facsimile are the initial applications for VoIP, the longer-term benefits are expected to be derived from multimedia and multiservice applications. For example, Internet commerce solutions can combine World Wide Web access to information with a voice call button that allows immediate access to a call center agent from a PC. In addition, voice is an integral part of conferencing systems that could also include shared screens, white boards, etc. Combining voice and data features into new applications will provide the greatest returns over the longer term.
Utilizing an IP–based network for voice traffic can offer advantages to consumers of reduced costs, simplification, and consolidation due to the proliferation of IP–based applications and devices at the desktop. These advantages are compelling for consumers and are driving service providers to consider VoIP implementations. In contrast, VoP over the ATM–based network offers distinct advantages directly to service providers and are still much more prevalent today.
