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Selecting VoIP for Your Enterprise

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Page 2 . All rights reserved. Service Provider Summary Glossary 3 3 4 4 5 6 6 7 9 10 Copyright ©2005 Technology Marketing Corporation.Selecting VoIP for Your Enterprise Prepared for Global Knowledge by Technology Marketing Corporation Table of Contents Introduction Cost Savings and Other Benefits Potential Pitfalls and How to Overcome Them Voice Quality Security Emergency Services/911 Network Outages Deployment: In-house vs.

By using the company’s data network.000 annual savings in operational expenditures over their previous system. the city spent $3. This presents a tremendous opportunity for numerous vendors to supply products and services to this market. that is enough of a reason to consider VoIP. and lower operational expenditures as a result of simplified management schemes. in the case of Mississauga. corporations are able to avoid the Public Switched Telephone Network (PSTN) and the associated tolls. Enterprises of all sizes can benefit from this technology. or across the globe. By converting voice into packets and transporting these packets over an IP network. But managing the system is simplified due to eliminating the need to monitor multiple networks. This paper serves as an introduction to VoIP (its benefits and potential pitfalls) and provides insight into the various options available to enterprise decision-makers who face the task of selecting a VoIP-based phone system. whether they are in the same building. All rights reserved. so too do the telephony applications that employees at the main corporate location enjoy. For example. or does it make sense to outsource to a hosted services provider? How much will this cost. you can speak to a distant colleague as if he or she were in the very next cubicle. Of course. According to the Probe Group. Page 3 . the ability to collaborate among multiple branch offices. Copyright ©2005 Technology Marketing Corporation. such as increased worker productivity. the market for enterprise VoIP will grow to $7.3 million dollars on a new VoIP network to serve over 2. The city is now enjoying a $700. this is especially true. but they must do some research to decide if VoIP is right for them. be it a private WAN or the Public Internet. Which vendor should I call? Would I rather deploy and manage my telecommunications in-house. Productivity enhancing applications such as conferencing. If the data network reaches a remote location. In the case of an enterprise with multiple branch offices. voice mail. cost savings come in many ways. thus enabling extension dialing between far-flung locations.000 phones. and how much money can I save in the long run? The first thing most people realize about VoIP technology is that it can save their business money by reducing or eliminating the toll charges for long-distance and even local calling. However VoIP is more than a plan to lower a company’s phone bill. VoIP enables seamless call transferring to experts across a connected enterprise. Ontario. unified communications. they can have all locations served by a single IP PBX. Tremendous cost savings come in the form of lower telephone bills. across town.1 billion in 2008. By simply dialing a coworker’s extension. enterprises can eliminate all costs associated with calling between branches. There are also so-called "soft" benefits enabled by VoIP. For many enterprises. and click-to-dial are all enabled across the enterprise. Cost Savings and Other Benefits The main benefit of VoIP technology is that it is a cost-saver. Furthermore.Introduction Voice over Internet Protocol (VoIP) is a process of digitizing and sending voice telephone signals over the Internet or other data network.

There are still impediments to voice quality that need to be addressed. here are the three culprits defined: Delay — The amount of time it takes for a signal to transfer or for the time that is required to establish a communication path or circuit. In fact. All without the need to call the phone system’s manufacturer to send a representative to make those moves. and latency. rapid variation in arrival time of a substantially periodic pulse waveform resulting typically from fluctuations in the wave speed (or delay time) in the transmission medium such as wire.By combining separate voice and data networks into one network. Let’s take a look at some of the more common problems experienced in a VoIP call: delay. and changes. jitter. It may not take much work to physically move a single phone or to set up a new employee’s voicemail system. and changes. Any problems that pop up in early phases of deployment can be worked out before migrating the next group of users. individual pulses appear to jitter or jump back and forth along the time axis. VoIP practically eliminates that expense. When the received pulse waveform is displayed on an oscilloscope screen. many VoIP deployments claim to have voice quality of service that is in some respects better quality than legacy communications. A thorough understanding of the potential return on your investment is necessary to ensure that the migration to VoIP is a cost-effective endeavor. but imagine an organization that employs thousands of people across multiple locations. adds. Furthermore. it is becoming less of an issue. allowing companies to migrate to VoIP slowly. While that has been a problem in the past. Another benefit of VoIP is that many enterprise telecommunications systems are upgraded in a piecemeal fashion. network administrators need manage only the single converged network. (2) The short-term variation of transmission delay time for data packets Copyright ©2005 Technology Marketing Corporation. or optical fiber. Potential Pitfalls and How to Overcome Them Voice Quality A serious reservation most people have is the belief that the quality of VoIP is inferior to that of traditional telecommunications. cable. According to Tehrani’s IP Telephony Dictionary. VoIP also reduces the cost and complexity associated with moves. a network assessment is in order. All rights reserved. Page 4 . In so-called "greenfield" deployments. The costs add up quickly. in order to maintain a healthy measure of control over the transition. Still the problem does not simply go away. there is no need to run two separate network cables (one each for voice and data). adds. Jitter — (1) Jitter is a small. VoIP enables cost savings from a network infrastructure perspective as well. For the vast majority of enterprises considering running voice traffic over their data infrastructure. In fact most businesses will need to spend some capital to upgrade their networks to be capable of delivering a consistent high-quality voice experience. department by department. Many enterprise VoIP solutions allow administrators to manage the system via a web-based browser interface and enable managers to enact changes to an employee’s phone and voice mail settings remotely.

That delay is imperceptible to the end user. Consider that if you send an e-mail that arrives with a two-second delay. and a score of 5 is excellent. (3) In IP telephony.0. And delayed or missing packets spell doom to quality VoIP communications. These servers are as susceptible to hacking or denial-of-service attacks as any other servers deployed in an enterprise IT department. acceptable delay for VoIP calls can be described as follows: • 0 to 150 milliseconds is acceptable for most any application. Certainly this is an area that needs to be addressed in any network deployment of voice. or mean opinion score. Security Security is another critical issue facing enterprises interested in deploying VoIP. The MOS rating system is judged on a five-point scale where a score of 1 implies poor quality. • 150 to 400 milliseconds is acceptable for international connections. Page 5 . it’s important to separate voice equipment behind firewalls—frequently updated with the latest patches and monitored to keep an eye-out for intruders. Still others believe that VoIP has a number of peculiarities that demand more specific attention. Copyright ©2005 Technology Marketing Corporation. Unacceptable! According to the International Telecommunications Union. Toll quality telephone service is generally granted a MOS score of 4. Also. So it is imperative to employ a quality of service solution that keeps the delay to an absolute minimum on the originating side of the call. vast amounts of potentially sensitive data would be at risk. All rights reserved. If troublemakers were to break into a company’s voice system. Other concerns include the "hijacking" of a voice gateway to place unlimited unauthorized free calls across the globe. As you can see.that usually results from varying time delays in transmission due to different paths or routing processes used in a packet communication network. eavesdropping is of great concern to executives who would prefer their phone calls to be as secure as possible. and as such is the goal to strive for. This measurement is determined by an actual group of human listeners who rate the quality of audio on samples played to them. the variance of interpacket arrival times. Latency — Latency is the amount of time delay between the initiation of a service request for data transmission or when data is initially received for retransmission to the time when the data transmission service request is granted or when the retransmission of data begins. Keep in mind that delay can creep in at many points throughout the network that are beyond your control. As such. Some industry professionals believe that VoIP in the context of network security needs to be addressed as simply another data application on that network. Now imagine that same delay in the middle of a conversation. all of these terms deal with the impediment to transmission of VoIP packets. Voice quality is calculated by a measurement called MOS. Most VoIP solutions are deployed on servers that run either proprietary operating systems or on commercially available servers such as those offered by Microsoft.

This is not the case for VoIP phone systems. or simply chooses to work from home? If an emergency call is placed to 911 from the caller’s new location. Customers have an expectation that they can reach you whenever they need to. But what happens when that employee. This way emergency services workers can respond to the exact location of an injured employee.The use of computer-based softphones. and taking precautions to secure your servers as you would for other critical business infrastructure and applications. who uses a softphone. chances are emergency service personnel will respond to the main office location—wasting time and valuable resources deployed to the wrong location. And phones might even be limited as to what type of calls they can place (international. it is necessary to factor this into your selection criteria. chances are the physical location would be in the same building. companies that are switching to VoIP have the expectation that their phone system will perform at least as well (if not better) than their legacy systems. There is concern among public agencies that system funding will come under attack as enterprises drop legacy phone services and deploy VoIP. and having that information transmitted to the PSAP. When selecting a VoIP phone system for your enterprise. there are a number of concerns for enterprises that should be addressed. Likewise. 900 number restrictions. Even if that employee switched offices and took his or her IP phone. VoIP phones demand a power source within the enterprise. User access should be controlled through password protection. If Copyright ©2005 Technology Marketing Corporation. The problem is that when power is interrupted. developers are tasked with the challenge of making sure that the speed of innovation does not outstrip the ability to supply emergency services to users of VoIP.) to make sure no unauthorized users can place calls if they are able to breach the firewall and get inside the network. travels to another city. keeping a close eye on your network through the use of an intrusion protection solution. VoIP users can avoid paying appropriate 911 surcharges while still using the service provided by their VoIP service provider. the phone systems will not work. Page 6 . and it is extremely rare for these phone systems to suffer outages due to problems with supplying electricity. All rights reserved. making sure your firewalls are properly configured. Another issue involves funding of emergency 911 infrastructure. Other general suggestions for protecting your voice traffic from security threats include: making sure to encrypt the voice stream. Enterprises can work around this shortcoming by assigning a physical location to each phone. Network Outages Traditional telephone systems are powered over the lines that are drawn from the local phone company’s central office. etc. which is not a problem. One current limitation of VoIP is that the caller ’s physical location is not broadcast to the emergency services’ PSAP (public safety answering point). Emergency Services/911 One of the more pressing concerns facing VoIP is the issue of emergency services such as 911. also leaves an enterprise open to a security breach. and even IP handsets. A business’ phone system is critical. While many consider this to be a service provider or residential customer concern. As VoIP enjoys rapid deployment. These devices should be encrypted.

giving users access to the office telephone system remotely or at the company. Users do not own the equipment. and it is imperative that you ask your provider to explain how they work and why they are important. With either choice. resides at the remote IP Centrex site. CT. Other power issues revolve around supplying power to the individual phones that reside on people’s desks. Furthermore. with either system. With IP PBX. As with buying or leasing a car. it amounts to nothing. Service Provider While there are many choices when it comes to enterprise VoIP. All rights reserved. when used in conjunction with a UPS. and remote management and monitoring. The decision depends on what’s right for your enterprise. Both approaches are viable. Power over Ethernet is able to supply power and data to IP phones. Gartner. whether IP telephone. with the exception of the telephones. regardless of geography or type of telephone. softphone. without the need to modify the existing infrastructure. Some of the solutions a business needs to look into are an uninterruptible power supply (UPS). high-quality power that will not degrade the telecom equipment. Power over Ethernet solutions abound. Essentially. you should consider outfitting your branches with UPSs in case localized power outages occur. These devices come with a varying amount of battery backup power. it is important to make sure that there are no disturbances in the power supply or else the quality may be affected at the branches. it is like leasing. This will help response time. Among the benefits provided by this technology is that it obviates the need to run power and data cabling to each desktop phone location. or wired phone. an industry analyst firm based in Stamford. They just want to know that their phones work. Lastly. Gartner also predicts strong growth in the enterprise IP telephony space with a 34 percent CAGR of Pure IP-PBX line shipments out to 2008. a remote monitoring system will allow you to see if there are any power issues within your network. as well as other devices over existing LAN wiring. and in fact most of the equipment.a new phone system with all the bells and whistles promised by VoIP sits idle for lack of a well thought out power plan. Furthermore. If multiple branch offices are served from a central server. the features reach across the network. you still get phone services and equipment with similar voice quality and reliability. redundant systems. Page 7 . not at the user site. this solution maintains power to the telephones for as long as the battery backup remains active. Copyright ©2005 Technology Marketing Corporation. and increase the ability to nip any problems in the bud. With IP Centrex. in the end the basic decision boils down to deploying the solution in-house versus having a service provider supply the solution in a hosted fashion (IP Centrex). Deployment: In-house vs. users buy the equipment and maintain it at their site. A UPS will continue to supply power to the phone system for a limited time until the main power is restored. Individual users probably will not even know or care if their company has IP Centrex or an IP PBX. predicts that business lines supplied as part of local VoIP carrier services in the United States (which includes IP Centrex) will grow at an 83 percent compound annual growth rate (CAGR) out to 2008.

There is not a steep upfront cost—but the cost is ongoing. With either IP Centrex or IP PBX. it becomes a major issue for the enterprise. adds. The one advantage IP PBX systems have is that because users can set it up themselves. It all depends on where the disaster takes place. With either system. say more than five years. there isn’t a clear winner. companies can have IP telephony in as many offices or home offices as they’d like. because the provider of IP Centrex services can be based anywhere and still provide services. if it occurs at the client site. both IP Centrex and IP PBX are very reliable systems. and because the IP phones can be plugged in anywhere. All rights reserved. because all the data and infrastructure is already built into the telephone system. Copyright ©2005 Technology Marketing Corporation. The jury is still out on what the best solution is for a company with multiple sites. IP Centrex providers charge much like a wireless provider. or changes. maintain. it should stay that way for a very long time.With IP Centrex. IP Centrex may be the best way for them to get the benefits of IP telephony. whether it’s an IP PBX or IP Centrex. Page 8 . For IP PBX systems. buying an IP PBX may make more sense. With an IP PBX. especially if it comes with the ability to migrate to future systems and/or grow to accommodate the company’s growth. but it also means that there is a learning curve. they have the control to establish the level of potential disaster recovery that is a priority for their business. For users concerned with disaster recovery and survivability. Since IP phones or softphones can be plugged in anywhere there is Internet access. if a company plans to keep its system for a while. Today. The upside is that once the system is running smoothly. it is typically less expensive to add new users than with IP Centrex. Geography does not matter. they can basically function as nodes off the home office’s IP PBX or from the IP Centrex. As with leasing cars. the upfront cost can be significant or it can be financed to make it more affordable. and learn how to use the system. IP Centrex can usually reroute calls very swiftly. For maximum survivability. What it really comes down to is preference: • If you want to own it a long time. billing a contracted monthly rate plus a variable rate for additional services. There is no doubt that ownership equates control. For companies that do not have the staff or bandwidth to implement an IP PBX. reliability. In fact. Calls need to be automatically rerouted when the system goes down. the user pays on a periodic basis. needs to be redundant and not physically co-located. Owning an IP PBX means there is a significant up-front commitment to install. security features have become a major consideration in today’s telecom decision. However. the system. users can move the phones wherever there is Internet access without the traditional service charges for moves. the IP PBX might be cheaper in the long run. Choosing a vendor plays a key role. IP Centrex systems are also very reliable during a disaster. users can be connected very quickly in the event of a disaster. and overall feature set. All these considerations should be factored into the total cost of ownership. As well. if the disaster happens at the IP Centrex Switch. without any geographic limitations. What does matter is the vendor’s reputation and track record for quality.

• If you want to keep the system a shorter time. Check out the following Global Knowledge courses: Voice over IP Deploying VoIP in the Enterprise Converging Voice and Data Networks Cisco Voice over IP Telecommunications Fundamentals I Telecommunications Fundamentals II For more information or to register. If you arm yourself with the right questions and a thorough understanding of your needs. buy the IP PBX. and many potential pitfalls that you need to be aware of before making the final move to VoIP. one needs to do some research before deciding on how to proceed. VoIP is the future of enterprise telecommunications. Choose from our more Copyright ©2005 Technology Marketing Corporation. Consider the trade-offs and be clear on what you really must have in your system today and into the future. from lower ongoing telecommunications bills to soft benefits such as increased worker productivity and the ability to conduct ad hoc collaborative sessions across multiple locations. • If you want special services or customization. Our courses and enhanced. and as with any major decision. hands-on labs offer practical skills and tips that you can immediately put to use.globalknowledge. as businesses who are shopping for phone systems are increasingly turning to VoIP as their first choice. • If you want basic services (calls in.com or call 1-800-COURSES to speak with a sales representative. Enterprises need to figure out if VoIP is right for them. visit www. Our expert instructors draw upon their experiences to help you understand key concepts and how to apply them to your specific work situation. IP Centrex might not cost you as much up front and you can contract for less time. All rights reserved. your migration to VoIP should be a positive experience. And if so. calls out) use IP Centrex. Page 9 . The decision depends on what’s right for your situation. which approach works best: hosted or in-house. enhance efficiency. Both approaches are viable. VoIP offers many benefits. yet both have their drawbacks. Learn More Learn more about how you can improve productivity. and sharpen your competitive edge. But telecommunications is the lifeblood of an enterprise. But there are many elements to consider when selecting an enterprise VoIP phone system. Summary VoIP is proving to be a viable new alternative to traditional telecommunications solutions in the enterprise.

The fiber optic transmis- Copyright ©2005 Technology Marketing Corporation. The service pedestal is said to be "at the subscriber's curb. WiMAX Magazine. and it usually refers to lossy compression. and subsequently recovering the original data (decoding). Firewalls vary in the amount of buffering and filtering they are capable of providing. WiFi Revolution. images.com publishes more than 25 topical online newsletters. About Technology Marketing Corporation Technology Marketing Corporation (TMC) publishes two magazines: Customer Inter@ction Solutions. Codec — Coder/Decoder A technique for compressing information to a fewer number of bits for more efficient transmission and storage (coding). WiFi Telephony Magazine. visit its web site at www." FTTH — Fiber to the home. and On-site sessions. Page 10 .com. delivered through Classrooms. and The Global Call Center Outsourcing Summit. CTI — Computer Telephony Integration. TMC is also the first publisher to test new products in its own on-site laboratories. and the online publications. all the way to the last 50-100 feet from the subscriber. TMCnet. and BiometriTech. or video. A firewall continuously looks for data patterns that indicate unauthorized use or unwanted communications to the server. Normally the term codec applies only to compression of human-perceived signals such as speech.than 700 courses.tmcnet. CLEC — Competitive Local Exchange Carrier. e-Learning. and Internet Telephony. The year over year growth rate of an investment over a specified period of time. A distribution system that uses fiber optic cable to connect telephone networks to nodes that are located in the homes of customers. Delay — The amount of time it takes for a signal to transfer or for the time that is required to establish a communication path or circuit. A distribution system that uses fiber optic cable to connect telephone networks to nodes that are located near homes or any business environment (near the curb). to meet your IT and professional skills training needs.com. SIP Magazine. Glossary CAGR — Compound annual growth rate. FTTC — Fiber to the curb. Speech-World. Alternative Power. The fiber optic transmission is used to provide broadband services beyond the central office. the Internet).g. Planet PDA Magazine. VoIP Developer. Speech-World Conference. All rights reserved. IP Contact Center Summit. TMCnet. For more information about TMC. A telephone service company that provides local telephone service that competes with the incumbent local exchange carrier (ILEC). TMC also produces The VoIP Developer Conference. TMC Labs. FCC — Federal Communications Commission Firewall — A firewall is a data filtering device that is installed between a computer server or data communication device and a public network (e. audio.

The G. ILEC — Incumbent local exchange carrier. IP Centrex — IP Centrex is the providing of Centrex services to customers via Internet protocol (IP) connections. and SIP. but offer clear advantages over TDM-based PBX. Copyright ©2005 Technology Marketing Corporation. Current IP PBX offerings vary in their range of features and network configurations. IP PBX supports both voice and data. and potentially a richer feature set. H. all the way through the drop wire to the optical node that is located in the customers home. It also describes signaling protocols for managing audio and video streams.sion is used to provide broadband services beyond the central office.723 — An International Telecommunication Union (ITU) standard for audio codecs that provides for compressed digital audio over standard analog telephone lines.711 — A standard analog to digital coding system (coded) that converts analog audio signals into pulse code modulated (PCM) 64 kbps digital signals.729 — A low bit rate speech coder that was developed in 1995. as well as procedures for breaking data into packets and synchronizing transmissions across communications channels. IP PBX — A private local telephone system that uses Internet protocol (IP) to provide telephone service within a building or group of buildings in a small geographic area. and data between a pair of videoconferencing workstations. Traditional PBX systems are voice-based. All rights reserved.323 is an umbrella recommendation from the International Telecommunications Union (ITU) that sets standards for multimedia communications over Local Area Networks (LANs) that may not provide a guaranteed Quality of Service (QoS). voice mail waiting indication and others. video. G. whereas their successor is designed for converged applications. The G. There are two versions of G. and voice mail along with integrating computer telephony applications.729 and G. IPBX systems are often local area network (LAN) systems that interconnect IP telephones. distinctive line ringing for inside and outside lines. intercom features. The G. mainly in terms of reduce Opex (operating expenses). A telephone carrier (service provider) that was operating a local telephone system prior to the divestiture of the AT&T bell system.323 specifies techniques for compressing and transmitting real-time voice. MGCP. Page 11 . IPBX systems can provide advanced call processing features such as speed dialing. IP Centrex allows customer to have and use features that are typically associated with a private branch exchange (PBX) without the purchase of PBX switching systems.711 standard was approved in 1965.323 — H. These features include 3 or 4 digit dialing. H. MEGACO. IPBX systems use a IP telephone server to provide for call processing functions and to control gateways access that allows the IPBX to communicate with the public switched telephone network and other IPBX's that are part of its network. G.711 standard allows for different weighting processes of digital bits using mu-law and A-law coding. IP PBX represents the evolution of enterprise telephony from circuit to packet.711 is an International Telecommunications Union (ITU) standard for audio codecs. G. It has a relatively high voice quality level for the low 8 kbps data transmission rate. It has low delay due to a small frame size of 10 msec and look ahead of 5 msec. call transfer.729 A. Some of the IPBX standards include H.323.729: G.

When the received pulse waveform is displayed on an oscilloscope screen. RBOC — Regional Bell Operating Company. The PSAP usually receives the calling number identification information that can be used to determine the location of the caller. maximum bit error rate (BER). rapid variation in arrival time of a substantially periodic pulse waveform resulting typically from fluctuations in the wave speed (or delay time) in the transmission medium such as wire. QoS — Quality of service (QoS) is one or more measurements of desired performance and priorities of a communications system. signaling processors. (3-IP Telephony) The variance of interpacket arrival times. PSAP — Public safety answering point. Good quality telephone service (called "toll quality") has a MOS level of 4. LAN — Local-area network Latency — Latency is the amount of time delay between the initiation of a service request for data transmission or when data is initially received for retransmission to the to the time when the data transmission service request is granted or when the retransmission of data begins. These stand alone devices plug into (connect to) data networks (such as the Ethernet) and operate like traditional telephone sets. MOS — Mean opinion score (MOS) is a measurement of the level of audio quality. A private telephone network used within an enterprise. An agency that receives and processes emergency calls.IP Phone — An Internet protocol phone (IP phone) is a device (a telephone set) that converts audio signals and telephony control signals into Internet protocol packets. The MOS is number that is determined by a panel of listeners who subjectively rate the quality of audio on various samples. A United States telephone company that is one of Copyright ©2005 Technology Marketing Corporation. Public telephone networks within countries and regions are standard integrated systems of transmission and switching facilities. All rights reserved. The rating level varies from 1 (bad) to 5 (excellent). minimum committed bit rate (CBR) and other measurements that are used to ensure quality communications service. PSTN — Public switched telephone networks are communication systems that are available for public to allow users to interconnect communication devices. Some IP Telephones create a dialtone that allows the user to know that IP telephone service is available. cable or optical fiber. individual pulses appear to jitter or jump back and forth along the time axis. ISP — Internet service provider Jitter — (1-general) Jitter is a small. PBX — Private Branch eXchange.0. Page 12 . and associated operations support systems that allow communication devices to communicate with each other when they operate. QoS measures may include service availability. (2-packet) The short-term variation of transmission delay time for data packets that usually results from varying time delays in transmission due to different paths or routing processes used in a packet communication network.

Pacific Telesis. bridges. and gateways. ROI — Return on Investment is a financial measurement that compares the profit with the original investment. BellSouth. RBOCs are also known as the Baby Bells.the seven telephone companies that were created as a result from the division of AT&T in 1983. Page 13 . and US West. Packet routing information is then added to the digital voice signal so it can be routed through the Internet or data network. All rights reserved. SIP — SIP is an application layer protocol that uses text format messages to setup. A UPS system is particularly important for network servers. the signal is first converted to a digital form. SMB — Small and medium businesses SOHO — Small office. SIP is a simplified version of the ITU H. ROI evaluates the impact of an investment on the telephone company's profitability or operational efficiency: dollars spent compared to benefits gained. home office UPS — A battery backup system designed to provide continuous power in the event of a commercial power failure or fluctuation.323 packet multimedia system. If the telephone signal is in analog form (voice or fax). Nynex. manage. SIP is defined in RFC 2543. VoIP — A process of sending voice telephone signals over the Internet or other data network. Southwestern Bell Corporation. The RBOCs were Ameritech. and terminate multimedia communication sessions. WAN — Wide-area network Copyright ©2005 Technology Marketing Corporation. Bell Atlantic.