The things you need to know to understand telephony today has changed. That should be pretty obvious to folks who read this column on a regular basis, but until recently, I didn’t consciously realize how much this fact has affected the other side of my business life, technical training.
With the rapid pace of telephony subscriber additions, much of my training energies over the past two years have been focused on making sure cable personnel apply best practices to customer premises installation, particularly house wiring. On that side of the industry, even though the embedded multimedia terminal adapter (EMTA) is a new piece of hardware, practical techniques have been around for as long as some folks’ careers.
Now that telephony is getting to be an established part of the cable telecom business, however, many of my clients are asking for what used to be called “advanced” telephony training. Even companies involved only with installation are expressing more interest in how telephony interfaces with other networks, including data and video. Way back when … In the old days, advanced telephony included discussions of the North American Numbering Plan (NANP) to understand phone number assignment, Signaling System 7 (SS7) for call setup and number portability, traffic engineering for capacity planning, and maybe virtual private lines as home office extensions to corporate phone systems. These topics are still important, but network and applications convergence are driving requests for training to subjects that diverge further from conventional voice topics. Since it may have been a while since you reviewed your own telephony knowledge bank, this feedback may be beneficial to updating your own training plan. Data To begin, if you don’t have a data background, you need one—even if you do nothing more than install residential phone service. Nothing that connects to a phone jack in the future will be ignorant of Internet protocol (IP), and you can’t afford to be either. In-home networking technologies like HomePNA, MoCA, and HomePlug have removed the walls between phone, PC and entertainment center. We’ll talk more about them later.
To understand IP, you need to understand the difference between a bit and a byte and how bytes are arranged in the unit of data transport called a packet. Then, to effectively troubleshoot, you have to know the effects of dropped and delayed packets, but more importantly, understand what causes those problems in your network. This is the content of a basic data course, which now becomes the pre-requisite for basic telephony.
Once you know the theory of packet transport across a network, you’ll want to apply it to practical troubleshooting, for example, to when your customer says the phone call sounds like it’s going through a tin can, or is echoing. To do this, you need to follow packets as they move from your customer to the called party. There are several graphic tools to help you follow voice packets through a network, but they all assume you know the meaning of IP address digit positions. This is the stuff you typically learn in your second data course.
(An interesting digression—many larger municipalities are facing shortages of conventional phone numbers caused by the proliferation of cell phones and number portability and are going to 10-digit dialing within a city. It’s only a matter of time before the problem becomes so great that the NANP will be replaced by the use of domain names similar to Web page addresses—all based upon IP addresses.) Home networks In the near future, you’re going to find that phones are becoming part of home networks or are sharing physical media with home networks. HomePNA, HomePlug and MoCA are the most popular existing wired technologies to connect devices on home networks, using in-home phone wire, electrical wire and coax respectively as distribution media. Wireless interfaces will also play a major role.
There are several implications to this type of network. One is the potential for contention between telephony and its multimedia cousins for available bandwidth before phone packets even leave the customer’s premises. Another is simple electrical interference. This is relatively new technology, and training is usually in the form of a seminar or trade show. At the headend As multimedia finds its way to residential applications (it’s beginning now with caller ID on TV), those of you that support telephony at the headend will need to understand the function of several types of servers and how they connect to your headend. You may already have experience with PacketCable call management servers (CMSs), but convergence is bringing a new architecture that includes policy servers for prioritization and authorization, edge routers to manage internetwork multimedia traffic, and third-party applications servers for new features that cross landline and mobile platforms.
Internet Protocol Multimedia Subsystem (IMS) is the current buzzword in telephony circles, and this technology is based upon server networks. (For more, see related story on page 24.) Network interconnection and communications between servers is the subject matter found in courses that prepare you for data certification by either a vendor or the SCTE. Certification Speaking of SCTE certification, the Society currently offers two telephony (voice) certifications as endorsements to core Broadband Premises Specialist and Broadband Telecom Center certifications. Although the SCTE doesn’t disclose the number of certified personnel, Joel Welch, SCTE director of Certification and Program Development, reports that a number of people have already certified for voice, and several are preparing for the exam. He also noted that a Voice Engineering Professional Certification, similar to the Digital Video Engineering Professional certification, is in the planning stages and may be offered later this year. The SCTE offers guidelines for areas of competence you will need to prove to be certified, but it does not deliver courseware specifically targeted to the certification exam. Seminars, symposia and chapter meetings are some ways the Society provides support for individuals interested in certifying. Other sources Where else can you find advanced telephony training? Professional training companies like Jones/NCTI, KnowledgeLink and others are good sources. So are vendors. True, all of them are going to cost you time and money, but the funny thing about a career is that it works like a good investment. The more you add, the more you get back. Justin J. Junkus is president of KnowledgeLink and telephony editor for Communications Technology. Reach him at firstname.lastname@example.org.