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Voice Over Internet Protocol: New Technology Streamlines Future Voice Communications by Jeff Carpenter, RCDD Voice over Internet protocol (VoIP) first appeared on the scene about a decade ago, attracting users with the promise of cheap, even free long distance using voice communications on the Internet. The initial experiments using this technology proved the possibility was there. However, actual user experiences have revealed that the technology still has some very basic flaws. Many users found the voice quality lacking. One of the reasons for the low quality was due to delays across the net in processing the packets, which caused latency and, at times, conversation loss. Another problem is that vendors still do not know all the answers to VoIP users’ questions. Questions like, Can an IP phone system possibly support the features of a private branch exchange (PBX)? Is it scalable? How can you be sure the system won’t crash under the strain of too many calls, or too much traffic? How does it handle 911 emergency calls? What about power and back-up power? These are very basic questions that most involved with VoIP are scrambling to answer. The vendors are working hard to overcome the shortfalls, and to bring to market viable and comprehensive solutions. However, many of the best features are just promises for the future. Yet, despite these concerns, VoIP continues to be one of the most rapidly growing technologies for internal and long distance communications. What Is VoIP? The next step in making a telephone call is to prepare the signal for transmission over the network. With VoIP, this means breaking up the stream into packets and adding the necessary information in place that allows the packets to move and be directed via IP. Legacy PBXs use proprietary signaling, which have little or no interoperability with switches of different manufacturers. VoIP however, has the advantage of using standard signaling protocols, which allows the call to move across networks of various makes and models. To set up a call, whatever system used must act on the signals it receives from the calling phone. Most VoIP solutions depend on a device that runs a sophisticated piece of software designed to manage, track, and facilitate the call. It also handles the conversion process between the addressing on the data network (IP) and the addressing on the legacy systems (International Telecommunications Union E.164 phone numbers). Vendors have different names for this equipment such as; call processor, gatekeeper, or softswitch, but generically this device is most often referred to as a call server. VoIP’s Gateway When making a voice call over IP, a user engages a phone set and causes it to transmit a state change (off hook, here’s a number, on hook). The voice stream is then converted to 1s and 0s and possibly compressed in the codec. Next, the voice stream is packetized and formatted for IP. It is then up to the call server to set up the call, locate a route for it to take, and monitor the call for state changes. Once the server has found a route and the call is up, the server should then make sure the packet stream is left independent of server function so that the server does not introduce any additional latency to the flow of packets. This problem of additional latency, which sometimes happens because a vendor solution leaves some of the calls running during the call slowing down the packet stream, does not always happen, but is something to look out for. If the call is leaving the IP network, it is routed to the gateway to
make the necessary media stream conversions for a PBX or the public switched telephone
network (PSTN), and sent on its way. The phone sets in most of the VoIP solutions are based on an open system architecture that allows for interoperability and interaction with other IP devices¾ including personal computers (PCs). This is especially important when it comes to managing and configuring the sets and developing user specific profiles. Many of the sets utilize this open system technology to incorporate on board Ethernet 10/100 switches. This allows the user to plug the PC or other network device directly into the phone set, in essence utilizing a single data connection for both devices. Cable Infrastructure Vendors currently use both voice-only, and voice/data combinations switches, running 10/100 Mb/s. Most offer gigabit or potentially 10 Gb uplinks, and because of the interoperability feature of the open system IP, the switches can then run on the existing Ethernet network. Additional redundancy may be necessary to provide for the “dial tone every time I pick up the phone†level of service. Redundant and high capacity links to the PSTN may also be indicated. Many local area network (LAN) router ports of 10 and 100 megabits are in service today, but appropriate bandwidth must be provided to eliminate latency. Also routers must be able to prioritize packets so that “on demand traffic†such as voice and video packets can run undisturbed across the links. Future Challenges Planning Ahead The most important step in the implementation of VoIP process is to ensure that the vendor you select is willing to do a fully functional pilot program. Bandwidth utilization studies, backbone redundancy issues, and quality of cabling infrastructure must also be evaluated to make sure the system will hold up under the strain. Also, a conscientious investigation into throughput across WAN links must also take place. This investigation must determine the number of WAN links necessary to provide a sufficient level of service. All of these factors must be accounted for during a cost/benefit analysis, to determine if VoIP can actually make a viable return on investment. Every vendor will claim that their products are solid, offer good quality of service, and are scalable and ready to take over the job of the PBX. In reality, it is probably a little too soon to throw out the PBX altogether and commit solely to a VoIP solution. However, with increasing interest in VoIP, designers need to be aware of and plan for this emerging technology. Their employers and clients won’t blame the vendor if their infrastructure is unable to move into the future. Hotel Changes, TCIM, 3rd Edition As we move into the second quarter of the year, much is happening at BICSI. The BICSI Brazil District Conference takes place April 18-20 in São Paulo and our 2001 Spring Conference is right around the corner on May 7-10 in Las Vegas. I hope to see many of you at these events. Speaking of conferences, there will be some changes in hotel arrangements for the Fall Conference. Read on. Hotels—Fall Conference While this is a new method for BICSI, other associations have used a housing bureau with great success. The participating hotels prefer this method and will give the special BICSI Conference rates only through the BICSI Housing Bureau. There is no additional cost to members or BICSI for this service, and BICSI does not benefit financially from this arrangement. Complete details and a link to the bureau can be found on the BICSI Web site, www.bicsi.org. The phone number is 800-424-5250. Details will also appear in the Fall Conference Preliminary Announcement, to be mailed in late April. TCIM, 3rd edition Working 15 hour days, the TI&M Panel 200 and the BICSI publications staff worked to provide the latest and most technologically correct information. One of the highlights of the editorial review was editing online. On behalf of our association, I would like to officially thank all those
involved, beginning with Panel Chair Ray Craig, RCDD/LAN Specialist; Allen Byrne; Richard
Dunfee, RCDD,Robert Faber, RCDD/LAN Specialist; Chuck Lohrmann, RCDD; Joe
O’Brien; Vic Phillips, RCDD; Mike St. Angelo, RCDD; Donald T. Wright, RCDD;
Charles Bowser, RCDD; Jacopo Lazzari; and Tim Sullivan RCDD. The Telecommunications Cabling Installation Manual, 3rd edition will be published in mid- 2001. Details will be in future issues of the BICSI News. English/Spanish Dictionary As always, I am here to serve you. Please feel free to contact me, the members of the Board of Directors, or the BICSI staff at any time. The Path to Wisdom May Be Strewn with Lonely Socks and Suicidal Hats To anyone who has ever done laundry, there is one mystery that eclipses
all others. I am happy to report that I now have an answer to this age-old question. But before I just blurt it out, perhaps a little background is in order. I was recently on vacation, wandering about in splendid isolation the roads less traveled of the South Island of New Zealand. Aside from being the very embodiment of paradise to my way of thinking, it has the added advantage of being about as far from everything as you can possibly get. So, imagine my surprise when I found myself in a laundry near Queens-town and discovered, just innocently sitting there piled in a corner, an enormous mound of socks. Single socks, mind you! Not a match in the bunch (yes, I checked… you can never have too many socks I always say). But then it hit me. This is where they go. This was the great sock graveyard whispered of in legend. I had always assumed they were just hiding somewhere behind the dryer, but no… my socks, your socks (one at a time, mind you) had found their way to the South Island of New Zealand. Mystery solved. What an incredible relief! One less of life’s persistent questions to check off our collective list. I just hope I don’t have to go to Kenya to find my car keys. And speaking of losing things—there is now a HellermannTyton logo baseball cap resting in 1,000 meters of water deep beneath the surface of Milford Sound. I know this because, just two minutes after my wife mentioned that I better hang onto my hat or it might blow off my head and land in the water (a ridiculous notion, and I told her so in no uncertain terms). Well, it blew off my head and landed in the water. Apparently a major portion of the reason for my existence is to provide entertainment to my family. Anyway, if the South Island of New Zealand is about as far from the rest of the world as you can get, Milford Sound is about as far from anywhere on the South Island of New Zealand as you can go. It is a beautiful fiord defined by mountains that rise from emerald waters, waterfalls that cascade down thousands of feet of sheer rock, seals that bask in the sunlight on rounded boulders… and now, one HellermannTyton baseball cap. As we toured the beautiful fiord, I couldn’t help but marvel at the short but eventful life of that hat. It had been worn only twice—once on a golf course in Florida (sadly, it shot an embarrassingly poor score that day) and a second time, halfway around the globe, on a boat in the middle of nowhere, near the end of the earth. Why the hat decided to commit suicide at that moment (I’m still thinking the golf score had something to do with it), we will never know. But years from now, when some future Jacques Cousteau discovers it while filming an underwater documentary on the last of the great New Zealand wood-boring sea barnacles, the world may sit and wonder how this artifact found its way to this place and at this time. Perhaps it was looking for one of its socks... Editor’s Note: Hot Topics in Print is a regular feature of the BICSI News. To suggest articles for this column, log on to www.bicsi.org, click on Online Forums, then click on Hot Topics in Print. Internet Week Cabling Installation & Maintenance Magazine Cabling Business Magazine Electrical Contractor |
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