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VoIP: Voice over Internet Protocol

©05 The Media Desk

VoIP in one sentence: Internet Technology which enables placement of telephone calls to and from traditional telephones, cellular phones, and other devices (fax machines) virtually for free using computers and data networks, now used by individuals, businesses and the phone company itself.


      The question about what will happen WHEN VoIP is implemented is moot. It is here and has been here for some time. Voice over Internet Protocol has been in use in various forms for over a decade and in fact, if you have made a long distance call anywhere in the last few years, your call was routed through VoIP for at least part of its journey.
      VoIP can be a heady topic and the debate over which protocol (H.323 or SIP) will win out is far from settled. Technicians wax poetic over various hardware platforms and just the catalog of circuits available for use as a backbone for a system can run several pages. This paper is far from a definitive treatment of the technology, but it should be enough to familiarize the reader with what it is and how it is used.

      1. What is it?
      2. Who uses it?
      3. How does it work?
      4. Problems and Issues with it.
      5. Future gazing.

1. What is it?

      VoIP is the wavy gray line where Voice Communications merges with the Digitial World of the Internet.
      VoIP stands for Voice over Internet Protocol. It is a direct descendent of the applications that allow human speech to be rendered digitally through audio sampling, transmitted through traditional data networks then reconstructed for playback on the other end.
      It has been used by large centralized businesses as well as government facilities and others with branches spread over a local area connected by high speed digital connections (such as multiple 'T'-class connections or direct fiber links) for some time. With this technology internal phone calls never touch the Telephone Company and thereby never generate a bill, as with a traditional Centrex or PBX system where each number is billed monthly and even billed per call per minute in some cases. VoIP also enables more call control and remote routing access which had been available with advanced, and expensive, PBX options. Using the LAN's connection to the Internet, internal calls can now be routed off-site, to any phone or computer in the world. Thusly the salespeople or managers can be directly in touch with the office just as if they were on site. Phone calls, emails, messages and even faxes can follow them wherever they go, in real time, and be instantly accessible through any internet connection, even over IP enabled cel phones or laptop computers.
      A branch of VoIP is Videophone Service. A real time service combining video images and voice transmissions sent digitally over existing connections allowing such things as Distance Learning and Video-Teleconferencing from multiple locations at once. Once the subject of science fiction shows, videophones are now in place in places as diverse as doctor's offices and criminal courtrooms.

2. Who uses it?

      Many local telephone service providers now convert many of their calls to VoIP for routing between local hubs and, in almost all cases, to long distance carriers.
      The old way of carrying telephone traffic over the switched network would tie up an actual pair of copper wires for the duration of the call. Even large cables only had a limited number of pairs available. This resulted in some callers getting "All circuits are busy" recordings during peak periods. Using digital encoding, one copper pair can carry dozens of calls at once. Using advanced techniques such as multiprotocol label switching (MPLS) that same pair of copper wires running a T-1 circuit can carry hundreds of calls in the same time frame. Thus the existing physical plant of copper wires and fiber optic cables, as well as microwave towers and satellites, can carry many times the original volume of traffic at a fraction of the cost to the company.

      Cost is a major factor in VoIP.
      To implement an in house VoIP solution on a single computer or even a small network in an office using simple Software Telephones (softphones) from a shareware or freeware source can be very inexpensive and, in fact, free if the computers all have speakers and microphones and the local data network can support the added traffic. With such a system the users would be able to call each other while leaving their existing telephones free for other calls. This would allow one employee to consult with another who may be in another office without putting the customer on hold and using another line on the phone, tying up two phone lines. If their LAN is connected to the Internet and their softphones use a recognized codec such as SIP or H.323, they will be able to place calls out of their facility to any other phone in the world. With more advanced equipment acting as a gateway and a PBX with a call management system, they could make long distance calls over the Internet and route their local calls out over their existing telephone lines.
      Of course more advanced features such as call management equipment and software, gateways, and dedicated circuits for voice call traffic cost more money.
      A substantial, full featured system robust enough for dozens of users or a call center environment with Call Accounting and other options can cost tens of thousands of dollars. IP phones can run several hundred dollars each. Training and support for the system and even an in house system administrator can add more expense to it on top of all that.
      Call centers such as many credit card and other telemarketing firms use with multiple sites, service redundancy, advanced ACD (Automatic Call Distributor) and IVR (Interactive Voice Response) features, and call accounting software can run into the millions of dollars before they make their first call. But once the system is in place and working, the ongoing expense can drop dramatically and the system's cost per call can become negligible leaving man-hours as the only major expense. Utilizing a well designed IVR system with automated messages that deal with the most common issues and problems, the person on the phone costs can be reduced.
      The call center can be anywhere in the world. Using VoIP, call routing can be an international event and the person calling the center never has to know it. They called the toll free number yesterday and their call was answered in Texas. They call it today and the call goes to the other side of the world. The call center employee brings up the file with the data from yesterday's call and the customer never has to know the difference. VoIP can be a true international service with the center's bill only showing the in country toll free charge, not an overseas charge.

3. How does it work?

      This is a very brief and simple description of the technical side of things. But it should give the reader some idea of how it all happens.
      A VoIP 'phone', does not have to be a traditional desk telephone at all. It can be a headset plugged into a computer, a cel phone, a microphone and speaker on a laptop, or even a fax machine (which uses many of the same protocols). Also, if the VoIP call leaves the data network to be routed to, say, a standard telephone at somebody's house, the re-assembly into traditional analog phone service will take place at the handoff between the digital network gateway and the POTS (Plain Old Telephone Service) phone system.
      The speaker's voice is 'sampled' by the VoIP device at rates of up to several thousand samples per second. Each sample is then digitally encoded into a data packet. Each packet is time stamped and addressed and is then routed over the Network to the recipient device where the samples are put back together in order based on the time stamp and then played to the receiving party.
      All of this occurs in real time. Voice packets are labeled as such by the system as they are time dependent, which email and spreadsheets are not. Packets received late or out of order by the device on the far end are discarded. Too many discarded packets create problems with the quality of the voice as heard by the receiving party and may make the conversation untenable.
      Due to the encoding and decoding, there is a measurable amount of time that passes between when a word is spoken and when it is heard on the other end. Also, normal silence is not transmitted. Very soft sounds, such as the sound of the other person breathing normally and regular background noise may not register and would not be transmitted. Thusly VoIP conversations can take on a different style than normal analog phones which were very good at picking up even minor background noise and carry it to the other party, lending depth and atmosphere to the call. With VoIP, when the other person is not talking, you don't hear anything from that side unless the system is using a coding scheme which allows 'comfort noise'.
      At one time a good VoIP call sounded like an average cel phone call. However, given the advances in the technology on both fronts, increased bandwidth available for use, and the more exact sampling methods now in place you may not be able to tell the difference. The quality of the call is now more of an issue of the age and condition of the equipment on either end than it is an issue of the method of the call's transmission from one to the other.

      One more point before we move on... The 'telephone number' of a VoIP phone does not have to be a seven (555-1212) or ten digit (with area code) phone number at all, it could be anything, even a sequence of letters or symbols, as long as the equipment (routers, servers, gateway etc) recognizes it and will route the call to the correct station. However, in this one case, convention reigns and most VoIP phones are assigned a series of numbers as their 'telephone number' within the 123-1234 format.

4. Problems and Issues.

      The downside is that VoIP traffic IS time dependent. It DOES take precedence over data traffic because conversations are not tolerant of data loss or delay. Even the comforting relative silence of comfort noise carried by the system uses bandwidth. During heavy use periods, data packets can be delayed or rejected. Available bandwidth and its allocation can become a major point of contention. Some LANs simply cannot handle the added traffic. Putting in more high speed connections to carry VoIP can exceed the savings on the phone bill.
      The administration of a VoIP system can become very technical very quickly. There are multiple points of failure. Fixes to problems may not be cheap or quick. Extended maintenance contracts and on site visits for upgrades or repairs can also add to the complexity and the cost of the system.
      One thing that is often overlooked is one of the main reasons people still use POTS service from the telephone company at home. When the lights go out, in the vast majority of cases, your Plain Old Telephone will still work. VoIP systems are entirely dependent on a constant supply of electrical power to the network they rely on as well as the various devices on it, such as the PC the headset is plugged into. They are not brown out friendly either. An uninterrupted power supply (UPS) system can be put in place to give time to take the system off line to protect it from surges when outside power is restored, but such a unit has to be installed on every server and router on the network. You can even use a backup generator to keep the system online during power failures. But the hardware used to keep a VoIP system running can be energy hogs. It is something that should be taken into consideration when planning a VoIP solution.
      A VoIP system can also be computer network dependant. If it is integrated into the LAN for true converged messaging, the voice network and the computer network can be one in the same system. Which is fine until a hacker gets in, or a computer virus crops up from an email, or even a glitch in the system erupts from an upgrade to a wholly unrelated application. In such an event, you may lose your voice and data networks in one stroke, and it is possible that neither will work until both are fixed. One other point is that any degradation of the system which data transfers might be able to forgive or overcome through error checking and retransmission of lost data caused by system latency or signal attenuation in a bad cable can simply kill voice operations.
      Another consideration is the interface to the PSTN (Public Switched Telephone Network). The link between the on site VoIP system and the PSTN should be able to handle the maximum traffic it is likely to face, yet still not be so expensive as to make it prohibitive. Many larger applications need at least a T-1 connection, which can be pricey. Some smaller sites can get away with a few analog trunk lines. One advantage to copper lines to the Central Office (CO) is that they are very stable and not prone to failure. The diagnoses of problems with those lines is very straightforward and repairs can often be made before the customer is even aware there was a problem. Higher capacity circuits not only cost more, they can be intolerant to errors and outside interference. Even worse, they can take longer to get fixed and are more likely to be out of service until they are fully repaired. There is no such thing as a temporary cable hanging from a fence for a fiber optic circuit that has been cut.

      Another problem with VoIP is that it IS international and for the most part, untraceable.
      VoIP call centers can be anywhere. If you dial US toll free number the number may never actually ring in the US. The call could be routed to whichever call center has an open line, be it in India, South Africa, or Latin America. Using a IVR system the call center can have you enter your own information to identify your account or even to help partially resolve your issue before their operator ever answers their phone. This can make customer Quality of Service (QoS) a concern and lead to some issues with the language barrier.
      Conversely, those same call centers, if operating for an unscrupulous telemarketer can employ VoIP to place calls to US numbers, irregardless of whether those numbers are on the Federal "Do Not Call" list. The center's programmers could also have set up the outward dialing programs to enter fraudulent ANI (Automatic Number Identification) information in the caller ID fields to make it appear that the call is originating in the called parties hometown with any name the programmers choose being displayed (Caller ID Spoofing). By doing this they have gotten around the US law and your call screening with Caller ID. Technology does exist to track through the IP address of the equipment that originates the outbound call, but even that data can be forged. If the call center and their sponsoring company are based in a foreign country, enforcement of the law can be all but impossible and most certainly not worth the effort for the penalty that will be imposed. And, true enough, some companies even see such penalties as simply the cost of doing business given the profits that result from making their calls.

5. Future gazing.

      The future of telephony clearly involves VoIP on both the small and large scale.
      Many home users are already using VoIP over their broadband Internet connection for long distance. It is also a viable option for some small businesses using their LAN and softphones.
      Many larger enterprises and government departments are already using or are in the process of deploying VoIP solutions.
      The only area not deeply involved with VoIP solutions is the medium sized PBX system environment. But as the cost of implementation comes down and smaller PC based systems are beefed up, the market for medium sized offices will open up and more solutions will be rolled out.

      Carrier-based systems will also continue to grow and even more local service will be converted to IP voice traffic.
      During the initial conversion of local switching to VoIP some prophets were saying that land line voice service would eventually be all but free to the public at large. But that hasn't happened, at least not yet. Between the use of IP for voice and data, there was also a proliferation of high capacity circuits like Frame Relay and OC-class services to businesses in the last several years. The problem has been that to support these services a lot of the existing infrastructure had to be replaced. Cables had to be replaced, switches upgraded, fiber paths run, and a lot of hardware purchased. The result of these expenditures resulted in much of the consolidation of carriers of the last decade. Those that could not build and grow were bought up by those that could and were. A lot of those costs were passed on to the end users.
      Today most of that build-out and build-up is done. There are fiber optic circuits run to places that had just gotten true touch tone service a few years before. Now high speed high capacity options are available almost everywhere and a good many businesses and schools are taking advantage of them.
      And to be fair, the problems discussed of disreputable use of the technology for some shady profits and even outright criminal operations will grow as well. The international law enforcement response to these problems must be focused on protecting the public from those that would use technology for their own ends regardless of the law. As with most things in the arena of developing technology, regulation through the various legislatures is a step or two behind the times. However, fraud remains fraud. There are laws on the books that can be made to apply to these types of crimes a they should be enforced.


      One thing must be kept in mind when dealing with the new technology. The goal is for people to be able to speak to each other. All too often the human factor is ignored or intentionally eliminated in favor of the technology as is the case with IVR systems. If the caller really wants or needs to speak to a live person they may not be able to negotiate their way through the prompts and menu layers to get to them. Sometimes the programmers fail to enable a 0-out (zero out) option in the menus to allow the caller to speak to a human operator. The IVR should be there to enable better and more efficient communication, not block it.
      Person to Person communication is the reason VoIP exists. If that factor isn't kept front and center in the development of the various solutions, a great deal of the benefit of the technology can and will be lost.

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