Chapter 39

Telecommunications Convergence

  If the telecommunication experts are unanimous on anything, it is the conviction that all forms of communication are gravitation toward a single unified IP network. There is less unanimity about when this transformation will be complete, but few expect it to happen overnight.both customers and carriers have too much invested in the PSTN to abandon it, and while the industry has solutions for most of the technical obstacles, the technologies are immature and changing steadily. Furthermore, the economics of convergence are insufficient to justify the capital expenditures of anything but an evolutionary transition.

     Historically, enhanced featurese have started in private networks and gravitated to the public. While the world lingered over ISDN standards, for example, PBX manufacturers brought its features to the office. The telephones and protols are proprietary, but the features are proven and available in every product line. The same is happening with the transition to IP. International Data Corporation (IDC) projects that about 1.4 million IP PBXs will be in service by 2008, but circuit-switched PBX lines will still outnumber IP lines by a factory of 3 to 1. Convergence faces fewer obstacles in the private arena because enterprise systems have shorter lives than public and the customer has better control of the infrastructure.

     Convergence in the public network, where switches typically have service lives of 20 years or more, is a different matter. The PSTN core is moving toward IP, but class 5 switches remain circuit-switched. ILECs are beginning to offer VoIP service over softswitches, but the motivation is more to meet competition than because of any technical advantage of IP. For what is does, the PSTN is good enough. It meets the needs of most residence and small business subscribers, and for voice alone it is superior to IP. Several factors are standing in the way of moving public voice and video to IP. The most important of these is the lack of a suitable for commercial-grade telephone service. The Internet is designed to be cheap and ubiquitous, but it is a chaotic model, not because of the behavior of the network, but because of the nature of the service. You can have low cost or QoS, but you cannot have both.

     Some observers suggest that the QoS issue is overblown, pointing to cell phones as evidence that people are willing to forego service quality in exchange for convenience. This observation is accurate as far as it goes, but it ignores two issues. One is that business-class telephone service demands consistent quality that the Internet is incapable of providing. VoIP over the Internet can supplement the PSTN, but it is not a suitable business model to replace it. The second issue is the fact that every telephone session has two parties. Some users may decide to forego quality in favor of low-cost Internet connections, which may be suitable for family and friends, but enterprises cannot afford to impose poor quality on their customers. The telecommunications industry has elevated transmission quality to its present state through a long series of technological advances. To diminish it for the sake of expediency would be a serious mistake.

     That said, the industry is evolving toward the converged network. It will be a gradual transition; one that will occur only after some significant barriers have been overcome. The obstacles will be resolved in time with more new protocols and a lot of industry work, particularly on the infrastructure. The Internet could be adapted for commercial grade telephone service, but several things would have to change. ISPs, which are competitive and independent, would have to agree to adhere to service and quality standards. Open interconnection with their competitors would need to occur and today`s pricing model would have to change. The Internet is designed and constructed to offer best-effort service at low cost and that is inconsistent with the needs of time-sensitive applications.

     Service quality notwithstanding, a growing amount of voice traffic is moving to the Internet as service providers such as Skype, Vonage, and AT&T`s CallVantage offer subscribers service at prices so low that millions are signing up. So what if the service is not toll quality. If people can call halfway around the world for nothing over a broadband connection that they have already paid for, some sacrifice in reliability is a small price to pay. Cable companies with their broadband access into most residences and many small businesses are in a particularly advantageous position to offer VoIP service because they have control of the access channel.

     VoIP in the public network is a disruptive technology. Although its impact has been slight so far, it forces the LECs to review their business models carefully. When a company can come from nowhere and furnish telephone service over a broadband connection with minimal investment, it causes concern for telephone companies and regulators alike. Regulators’ traditional modes of taxation and control are impossible with Internet telephony, at least at this point. In 2004 the State of Minnesota attempted to impose telephone regulation on Vonage despite the fact that the PUC`s control does not extend to interstate calls and it is impractical to segregate VoIP calls. This prompted the FCC to issue an order preempting the Minnesota order, but the issue has not been put to rest.

     In this chapter we look first at the forces that are driving toward a converged network. We look at services that countries such as Japan, which has a much higher degree of broadband development than North America, are beginning to provide and how these motivate the development of the converged network. We examine the advantages of convergence and the barriers that are impeding its development. We look briefly at the Infranet, which is an initiative of several companies to develop an IP-based alternative to the Internet. The Infranet, if it is successful, may prove to be the enabling factor that removes most of the barriers. We conclude the chapter with an Applications section that discusses the ways in which the converged network is available today and considerations in applying it.

WHY CONVERGENCE?

Above the physical layer, the Internet is diametrically opposite the PSNT in most ways, so why is the push on for convergence? The answer lies in a complex brew of economics, politics, culture, and technology. The term convergence holds different meanings for many people, so let us begin this section with a definition.

Convergence.  Merging real-time applications such as voice, video, and instant messaging together with data onto a single broadband infrastructure that is based on IP.

     The reasons for the trend toward convergence are many, not the least of which is an urgent need of  manufacturers to find innovative new products to help them emerge from the technology slump that began in 2002. This is coupled with the zeal of the international Internet community that is persistently pursuing a vision of a unified network. Companies that see expanded opportunities for innovation in such online applications as gaming, music, television, education, and countless services that have scarcely been glimpsed support this vision.

     In 2004 NTT DoCoMo introduced services in Tokyo that give us a preview of the kinds of applications that converged services make possible. Dubbed “Felicia,” the service marries a 3G handset, a smartcard, and GPS to enable users to perform a variety of functions that are otherwise impractical or require separate devices. The smartcard, coupled to the target by wireless, is loaded with identification and financial information that enables users to make purchases from vending machines, payments at restaurants, and to board trains and buses without tickets. A user standing at a bus stop wondering when the next bus will arrive can link to the transit company to obtain the answer. The mobile handset provides its location from its GPS and the application compares it to the bus’ location, also obtained from GPS. Users can purchase tickets to events, locate restaurants and shops in their locale, nad link to RFID devices in the store to download more information about the products. Devices such as these will change the way we work and live, and the functions are impractical without a converged network.

The Business Case for Convergence

Convergence has a lot of appeal for the enterprice. If its promise is realized, operational costs will drop and better utilization will be made of an expensive resource. An all-IP network will allow service providers to create new value-added services. Much of the time-consuming provisioning process will become unnecessary as the network evolves to respond dynamically to changes in demand. Business models will change and new ones will emerge as inexpensive and ubiquitous bandwidth becomes available. In some countries with extensive broadband access, for example, the market for downloaded music exceeds that for CDs. Video rentals will fade in favor of video-on-demand, and presence engines that advertise personal preferences for reachability will drive personal communications. Barriers to entry of local phone markets will disappear as consumers move their telephone service to IP networks, and the phone will be a multimedia device more or less permanently associated with an individual, possibly with the address issued at birth. Let us look in more detail at these benefits.

Competitive Advantage

For some businesses, convergence is necessary to support business goals including reduced cost of doing business, increased productivity, and improved customer service. A converged network supports collaboration with customers, which results in improved customer retention. Businesses can tie customers to their internal processes through e-commerce. Multimedia contact centers can enable organizations to create an on-line experience that approximates face-to-face services delivery, enabling the customer to choose the preferred method of communication and shift to another mode in the middle of a session.

     At firs the converged network will catch on slowly with the early adopters gaining the most advantage, but gradually it will change the business model to the point that customers will expect the service. Today in Japan’s Felicia service, for example, a customer can surf the Web from her 3G phone, inspect a photo of a product, order it, and pay for it, all from the same hand-held instrument.

Lower Cost of Ownership

The cost equation is difficult to factor into the decision to migrate to a converged network. To realize cost reductions, cultural changes and dedicated management effort are required. The following are some of the ways ownership costs can be reduced:

·         With only one unified network infrastructure to design, manage, and support, labor costs should be reduced. The same staff that support servers, switches, routers, and LAN equipment can maintain the voice switching system, and reduce or eliminate the need for outsourced expertise.

·         Users can do many of their own moves, adds, and changes without involving the IT staff.

·         A converged network enables enterprises to make more effective use of access bandwidth, while simplifying administration and maintenance.

·         Host-based services can eliminate the need to invest in a dedicated PBX or upgrade an obsolescent system, while still providing the productivity enhancements of feature telephones.

·         Call processing can be centralized for multiple independent sites, eliminating the need for separate key systems, resulting in lower branch office costs.

·         The quantity of station wiring drops can be reduced by combining both PCs and VoIP on the same Ethernet port.

·         IP PBXs are more scalable than TDM PBXs, which have a maximum size and grow to that size by adding port cards and cabinets.

Support a Mobile and Geographically Independent Workforce

This advantage is important for telecommuters, sales people, and others who spend a great deal of time away from the office and to people who work from home at least part of the time. It is particularly difficult to provide conventional voice communications that are integrated with the office telephone system to such people. With VoIP the benefits of the PBX can be extended outside the bounds of the office. The need for office space is reduced and the organization is able to comply with government regulations that require employers to reduce traffic congestion. Part-time people can work from home to supplement a fixed call center workforce.

Flexibility

The TDM PBX is a proprietary and inflexible device, closed in every respectexcept for its CTI interface, which provides for limited call control. Although IP PBXs (with the exception of open-source system) do not open their call-control programs, they provide more flexible interfaces such as SIP to permit development of server-based features. They also open options for branch and home offices that are expensive or difficult with traditional architectures.

Create Value-Added Services

Convergence opens an enormous variety of opportunities to provide new services that are infeasible with circuit switching. The user interface for telephone service has improved little over the years. This is not because of a lack of imagination on how to improve it or a lack of APIs for hooking new applications to proprietary systems. It is more because the applications must be customized for each type of CPE system, and no manufacturer has enough market share to generate a mass market. For example, unified messaging has been available for years, and there is little variance in the features that various products support, but it has not achieved enough market penetration to bring the cost down to the point of becoming popular. Open protocols such as SIP can separate the services from the call control, which by its nature must be closed. Carriers and third-party developers can create countless new services and make them operable across a variety of platforms.

Enriched user Experience

Ultimately, new services will change the way people work and communicate. Personal communication assistants can enable critical employees to be contacted while still screening unwanted calls without the need for human assistance. Functions that are difficult with a standard telephone interface, such as setting up conference calls and dialing by directory name, will become easier with an improved user interface. Productivity should improve through remote collaboration and shared access to documents or whiteboard. Just as the PC is a standard office tool today, these new applications will become such a way of office life that users will expect them to be available.

Rapid Deployment of New Applications

New and innovative applications can be deployed more rapidly with IP than with traditional fixed telephone systems, and the pace of improvement does not depend on the actions of a single vendor. Furthermore, in a geographically dispersed organization, new applications can be downloaded onto desktop clients without involving a generic program upgrade.

Barriers to Convergence

New telecommunications developments have always been over-hyped, and with notable exceptions such as fiber optics, many of these have flared briefly and fizzled out. After an initial period of exuberance, convergence is proceeding slowly for a variety of reasons, not the least of which is the difficulty in demonstrating a suitable return on the investment. Most of the advantages listed above require the organization to change and adapt to a new environment, and this often happens slowly.

     The initial impetus was long distance cost saving, but that argument has largely disappeared now that long distance costs are so low. Savings from managing the converged network are difficult to prove unless the workforce shrinks with the new technology. When ROI is calculated, many of the savings are in soft dollars and demonstrating real cash saving is more difficult. Convergence will develop in time, but many issues listed in this section remain to be resolved.

Network Infrastructure

Carriers are converting portions of their network to VoIP cannot support the performance and security that commercial-grade voice communication demands. For VoIP to be a viable alternative to the PSTN, it must support carrier interoperability. For services such as worldwide VPNs and telephone connections to be effective, they must transcend carrier boundaries because no carrier has sufficient reach without relying on other service providers. Carriers therefore must be able to interconnect with appropriate levels of security and service definition and the sessions must be metered to compensate carriers for handling transit traffic.

     Today, many outsiders expect the Internet to become the backbone for this multiservice, multinational, multiowner network, but those expectations are unrealistic. A network converged over IP does not mean the public Internet as it is now structured. Obviously, it can carry voice. It does it every day, but it cannot carry voice with the consistent quality that the world has enjoyed since the conversion to an all-digital network. The alternatives are developing an overlay network that has the stability isochronous applications need, or hardening the Internet. The latter means changing the basic design concepts that keep the Internet cheap and fast-paced.

     Peering points on the Internet today do not meet any specified performance criteria and there is no incentive to support a guaranteed level of service. The converged network must provide an appropriate level of assured delivery in response to requests from the application. This is inconsistent with the intent of the Internet, which is to deliver inexpensive connections that are not sensitive to usage or distance. Either the Internet must be split to provide a separate network with reliability and security, or the cost of service must increase.

Flow Control

Another key issue is congestion control, which is a vital feature of any voice or data network. The difficulty is that voice and data behave differently when it comes to congestion. Both can throttle traffic back at the source, but the nature of the traffic flow is much different.many data applications have peaks af high bandwidth demand for short intervals, but then demand drops to zero as the user operates on a downloaded file. If the network is congested, it is apt to be for only a brief interval, after which traffic begins to flow normally. During the heavy flow periods, TCP closes its window or routers discard traffic, but the process is transparent to the users, who see a slow response, but the session continues without interruption.

      Unlike data with itsheavy peaks, voice is a relatively even flow of half-duplex traffic that is predictable. Traffic engineers have mounds of data that enable them to predict voice loads by hour, day, and season until something unusual happens. Storms, disasters, significant news events, and other external events usually inspire an extraordinary number of customers to place telephone calls. These cause traffic to fall outside the normal range and the network has to protect itself while prioritizing service to essential customers. Voice networks shed load by a variety of techniques, the first of which is to delay dial tone. During heavy load periods the LEC can operate line-load control, but this is done only in extreme circumstances. Common-control equipment such as DTMF registers are engineered for normal peaks. In abnormal peaks, the registers may be tied up, so the caller does not receive dial tone. The caller can remain off the hook and dial tone will eventually be provided. If the congestion is in the trunking network, calls will not go outside the serving class 5 switch. The user hears reorder and must redial.

     Flow control is a standard feature of TCP, but real-time packets work under UDP, which does not provide flow control. An IETF working group is working on Datagram Congestion Control Protocol, which is intended as an alternate transport protocol. DCCP offers functions that bridge the gap between TCP and UDP. These include packet acknowledgement, congestion notification and control, packet sequencing, and protection against denial-of-service attacks. This protocol may resolve flow control issues.

Security

This is the issue that is the most difficult to resolve on the Internet, while still keeping the service manageable. While users must get involved with encryption, tunneling, firewalls, and similar security provisions, VoIP will be confined to a narrow spectrum of users that are willing to put up with the complexity in exchange for the benefits. A major strength of the PSTN is the fact that uninvited guests cannot ride the coattails of a file or message, latch onto the telephone, and infect it with a virus. While trust is not an issue with the PSTN, eternal vigilance is required on the Internet to thwart a coterie of miscreants who, for whatever malevolent motivation are  attempting to inflict damage.

Broadband Penetration

For VoIP to be successful, broadband must become nearly as ubiquitous as the PSTN. In 2004, the latest figures available as this book goes to press, broadband penetration in the U.S. is reported to be 42.5 persent of households with Internet access. About three-fourths of households have Internet access, which means broadband penetration is roughly one-third of the households. Other countries, notably Sweden, Japan, and South Korea, have penetration in the order of three-fourths of all households, significantly greater bandwidth, and at a cost that is more affordable than in North America. This issue must be resolved before the converged network can claim success.

Service Complexity

For VoIP to become universally accepted, it must be simplified. Today, customers need to know too much about VoIP to make it work. The strength of the PSTN is its simplicity. Customers do not need to know anything about addresses, E-911 access, NAT, and other such technical issues to make the telephone work. For VoIP to be ready for real time, users must be able to plug the service into a wall jack and have it work without the need to configure firewalls, install VoIP terminal adapters, or worry about IP addresses. Users must be able to connect to other VoIP users without using the PSTN as an intermediary and without the need to know the identity of the callee`s service provider.

Lack of Carrier Agreements

IP networks are today a loose confederation of agreements among carriers. A carrier-class VoIP network cannot depend on a service provider`s decision whether to carry transit traffic. This, in turn, means that international division of revenue processes must be developed. Competing carriers must deal promptly with impairments and failures and must cooperate to ensure that service is not affected by the structure of the interface points of diverse networks.

Carrier and Regulator Inertia

The existing PSTN infrastructure works well, represents a considerable investment, and is maintained and managed by workers that lack the skills to manage an all IP infrastructure. ILECs, in particular, will retain what they have until it is functionally obsolete or competitive pressures force them to change. Numerous other forces resist change. Congress is subject to numerous presseures that affect the shape  telecommunications will take, and money is at the root af it. Cash-rich companies such as the ILECs have the ability to inject huge amount of money to purchase influence and they have been successful in this endeavor.

     The regulatory framework is based on conventional telephone technology as are structure of traxes and fees and these tend to change slowly. Much of the economies of VoIP in the U.S. today result from Congress’ reluctance to burden IP with the fees, restrictions, and taxes that it loads on the conventional telephone industry. Access charges, USF fees, excise taxes, and myriad state and local taxes, not to mention carries’ miscellaneous fees complicate the picture. Moreover, regulations are inconsistent. LEC cable pairs are subject to unbundled access regulations, but new fiber investments are not. Cable companies can prohibit other carriers from using their access facilities and have both the ability and the motivation to exclude other providers from using them for VoIP. All of this creates an atmosphere in which progress is impeded because there is little assurance that the rules will not change.

Reliability and Availability

IP networks are inherently robust with their ability to route around failures, but router convergence time is too lengthy for real-time applications. Operational changes such as hardware and software upgrades and configuration changes cannot be done in real time with many router platforms. The solution requires a new generation of routers and protocols, which will be slow to propagate themselves through the network.

Compliance Issues

Making VoIP comply with E-911 and CALEA is a major unresolved problem. Many countries censor Web content, block access to certain sites, or monitor access to parts of the Internet. These requirements are incompatible with using the Internet as a reliable communications channel.

Interworking between the PSTN and IP

Until the transition to an all-IP infrastructure is complete, communication between the two networks is required. This requires gateways, signaling, addressing, and numerous other complexities that must be transparent to the users. Much work remains to be done to make the interface with the PSTN seamless.

THE IPsphere INITIATIVE

Many of the changes necessary to make VoIP equivalent to the PSTN require voluntary or compulsory adherence to centralized authority, a concept that is anathema to the Internet community. If we conclude that the Internet in its present state is not an appropriate vehicle for isochronous traffic, then the solution may be an overlay network that is designed to provide the elements missing from the Internet: QoS, predictability, end-to-end management, security, and carrier interconnections with division of revenues or settlement process. Such a network would not be accessible from the public Internet and would provide the benefits of IP without subjecting its subscribers to the chaotic conditions that prevail on the Internet today.

   An initiative known as the IPsphere, previously known as the Infranet is underway to create such a network. Equipment manufacturers and carriers are not unanimous in their support of the IPsphere and there is no assurance that such network will happen. The goal of IPsphere is to deliver performance over a virtual network that is predictable, flexible, and secure so subscribers can entrust mission-critical informations to it. At the edge of the IPsphere is a barrier that requires customers to authenticate themselves before admission.

   The IPsphere requires communication between the subscriber’s application and the network to enable the application to request the level of secureity, quality, and bandwidth it needs. Costs would be based on what the application needs, in contrast to the Internet where the cost is independent of the application. Since no single provider can guarantee worldwide connectivity, connections are needed between networks so providers can communicate levels of service and security when handing off traffic. In addition, accounting mechanisms are needed to enable carriers to bill each other for carrying traffic.

Convergence application issues

The motivation for the converged network in the enterprise network can be summed up in one word: productivity, both of personnel and capital. In the public network the motivation is also clear. For consumers it is saving money and getting enhanced services. For service providers it is the opportunity to make money. It will be many years before the technology has advanced to the point of replacing the PSTN for more than a narrow spectrum of users, but the obstacles will gradually be surmounted.

VoIP in the Public Network

At this stage of development, the ways of implementing VoIP are many and varied. From a residential or small business user’s standpoint the ideal would be to connect a VoIP telephone into a wired or wireless LAN, assign it a telephone number, and user it as if it were a wired phone. The reality, however, is considerably different. Several companies have jumped onto the VoIP bandwagon and by the time this is published, many more would have joined the fray. IDC estimates that by 2008 some 14 million customers worldwide will subscribe to VoIP services. In this section we briefly discuss the alternative configurations and some of the considerations in selecting them. The services they offer are changing, however, so it is best to refer to the vendor’s describtion on its Web page before relying on this discussion.

Computer-to-Computer Services

Representative services include Pulver, Skype, and Dialpad. These services generally cannot be reached from the PSTN because the user does not have an E.164 number. In the process of registering with the service provider, the user obtains an address that is valid within that network. Calls within the network can be made to others who have registered and are online.

   The telephone instrument is usually a softphone and client, which can be downloaded without cost. These services usually do not carry a monthly fee, although some offer off-net prepaid packages. PC-to-PC calling is free. Calls that hop off to a wireline phone carry a charge that is usually much lower than small users can obtain, but may not be much of a saving for large users. The greatest savings are on international calls. Features include buddy lists, redial, and running account balance.

   Firewalls and NAT generally do not bother these types of service because nothing identifies the call as a voice call. To place or receive calls the user logs onto the provider’s Web service, so the session looks to the network like any other Web connection.

Computer to PSTN Services

Representative services include AT&T CallVantage, Vonage, Net2Phone, and Go2Call. A major difference between these and computer-to-computer services is the provision of an E.164 number, which enables the IP phone to be called as if it were a wireline phone. Since the service provider controls the design, the portion of the call that uses the Internet is under its control, so the service provider can control the quality. The architecture is invisible to the customer, so there is no way to evaluate the service in advance except to try it.

   Some products permit or require the use of a VoIP terminal adapter, which connects an analog phone to the network. Some will work with downloaded softphone products. In most cases existing numbers can be ported to the IP service, and the IP phone is not tied to a physical location. This means it can be transported to another place and operate as it does from the primary location. Vonage offers a virtual in certain local calling areas. This permits someone with a landline telephone to make a local call, which is transported to the destination across the Internet.

   Most of these services carry a monthly rate, which may include unlimited domestic calling. The rates are generally lower than LEC phones, and may include a package of special features that the LEC charges for. Voice mail is typically available, with message retrieval from either telephone or browser. Voice mail messages can also be forwarded as e-mail attachments. Other typical features include caller ID, call forwarding, call logging, do-not-disturb, conferencing, and locate service.

   The service has much in common with cell phone service. Most users will not give up their PSTN phone, but it is a good for a second line. The service has several downsides that must be considered, not the least of which is lack of compatibility with E-911. In addition, it does not work through power failures. If the line is to be used as an additional line throughout the house or business, the adapter must be wired in place, which defeats the easy portability. Finally, the service is not as simple to set up as buying a telephone and plugging it in. the author’s experience with AT&T CallVantage is a case in point. After several hours of attempting to make it work through Comcast cable, the AT&T technician gave up concluding that Comcast’s routers were blocking the service.

TDM over IP (TDMoIP) Multiplexers

    Several manufacturers provide TDMoIP multiplexers for applications such as the one shown in Figure 39-1. Here, the company has an Ethernet connection between sites and T1/E1 compatible. PBX and key systems. The IP multiplexers connect to the CPE devices with TDM and to the Ethernet switches with 100Base-T, sharing the bandwidth between sites with data. The multiplexers shown use T1 on both ends, but they could just as easily use analog trunks, in which case the connection would typically be FXS/FXO. The TDM frames are encapsulated into IP packets that are transported over the fast Ethernet ports. The ToS bits of the packets are set to classify the packets as high priority.

    TDMoIP provides a circuit-emulation service, also called pseudowire, that is transparent to protocols and signaling. The multiplexer repeats the contents of each channel to the other end. The IETF PWE3 Working Group is working on protocol standards that are in draft form as this book is published, so products are likely to be proprietary. Typically, the payload of each channel connects to a 48-octet ATM cell, which does not have the 5-octet header. These are encapsulated into IP frames in some multiple. As the number of TDM octets per frame increasesthroughput increases because of lower packet overhead, but the effects of frame loss are more severe.

   Compared to VoIP gateways, TDMoIP multiplexers have lower latency, so the circuit quality is likely to be better, provided packet loss is not excessive. As with VoIP gateways, the multiplexers compensate for packet loss by repeating the contents of the previous packet. The multiplexer transmits channel timeslots whether they are empty or not, so from this standpoint it is less bandwidth-efficient than VoIP. The impact of this generally irrelevant, however, because a TDMoIP multiplexer is not used where bandwidth is restricted. For example, it would not be usable over the Internet. Some products support fractional T1/F1 so vacant channels are not transmitted.

VoIP Business Applications

VoIP has four principal categories of applications in the enterprise network:

v  Branch office. Since the branch office is already equipped with a router or FRAD, adding voice may be a natural outgrowth of the existing network. For distant branch offices, the existing frame relay network may be used. For local branches, it may be feasible to replace off-premise extensions with VoIP.

v  Telecommuting. Similar in architecture to the branch office, telecommuters may use VoIP to provide a voice and data connection to the main office.

v  Toll bypass. Carrying long distance traffic for next to nothing is attractive, particularly when the distances are great. The ability to send large quantities of fax messages, which tend not to be time sensitive, over the Internet, can be particularly attractive.

v  Web-enabled call center. Callers can browse the company’s Web page by computer, and then click an icon to talk to a live agent. Costs are reduced and customer convenience is enhanced.