Telephony Knowledge Benchmarks

Certification keeps growing in importance as a benchmark for technical ability. Perhaps the proliferation of "easy" degrees has made it necessary to create industry-sanctioned programs, rather than academic ones, to provide a sense of security for potential employers (and consumers) that an individual really does know his or her chosen craft. Whatever the reason, telephony is no exception to this trend, and the SCTE is meeting the need with voice endorsements to its core Broadband Premises Specialist (BPS) and Broadband TelecomCenter Specialist (BTCS) certifications. The challenge, however, is to keep both the certification and its associated testing program current as technology moves. Over the past couple of months, I have been working on this process for telephony with SCTE, and this column will give a preview of what is coming, particularly in the voice endorsement to BPS. As you probably recall, BPS covers "tap to TV set," or more accurately for the voice endorsement, "tap to telephone." The original voice endorsement outline is now more than three years old, so you should anticipate there will be some differences from the old version of what is expected of an SCTE voice certified tech. By the time this column is printed, SCTE should be very close to publishing a final version of the new study outline for BPS voice. Similarities Some things won’t be much different. There are still five major categories of knowledge tested: public switched telephone network (PSTN), customer premises equipment (CPE), fundamentals of broadband telephony, installation, and troubleshooting and maintenance. The focus is on residential telephony. Within the PSTN category, a BPS with the voice endorsement is still expected to know the hierarchy of a telephone number as defined in the North American Numbering Plan (NANP). On the surface, this might not seem important now that number portability and voice over Internet protocol (VoIP) has made geography irrelevant, but consumers still recognize neighborhoods by phone numbers, and there is a large base of circuit-switched equipment that is linked to exchange/office codes. Technology has not changed the requirements for call setup, signaling and ringing. At the tech level, the "need to know" is limited to understanding that off-hook indicates a request for service or an active call, that there are two basic types of busy signal, and two types of dialing. Similarly, custom local area signaling services (CLASS) features and voice mail are still important parts of telephony offerings. In fact, the new outline will add a couple of features as specific examples. The reason these features are important to an installer is that they are services that originate in our networks, rather than at the customer’s equipment, and will be part of a service order for telephony. For a similar reason, the outline no longer requires a knowledge of features that can be provided at a station set, since that is a customer responsibility. Surprisingly, the need to understand constant bit rate (CBR) telephony hasn’t gone away, despite the growth of VoIP and its carrier class IP voice version. The reason is that there is still plenty of CBR telephony in the field, it works well, and it needs support. That means a tech with the voice endorsement must know how to install a CBR cable telephony network interface unit (NIU), understand how it communicates with a host digital terminal (HDT), and how the NIU is powered, either via network power or local battery. Now, here’s an item that points out how things do change. Five years ago, most operators were concerned about the reliability of local power for the NIU. I don’t know of any cases of network powered embedded multimedia terminal adapters (EMTAs). As part of CBR knowledge, it’s necessary to understand time division multiple access (TDMA) multiplexing, which is very different from the way IP voice works. Personally, I’m delighted this subject remains in the endorsement requirement because it forces a tech to understand the theory behind voice transport in the access part of our systems and to better appreciate the value of IP for handling multimedia as well as telephony. New stuff Let’s look at some of the new stuff. Under the PSTN heading, we no longer refer to a voice switch, but to a more generic "Class 5 local office switch." This opens the topic to include servers as well as circuit switches and retains the commonly used terminology of Class 5 local office. Under the local loop subcategory, the tech is expected to know about technologies that use frequency assignments on copper pair outside the voice range, such as digital subscriber line (DSL) and HomePNA. The reason is possible interference in homes with multiple service providers. Finally, the outline includes separate PSTN bullet points for the Communications Assistance to Law Enforcement Act (CALEA) and E911, which are important consumer issues that an installer may be required to discuss with a customer. Under the category of CPE, the outline no longer groups telephone station set components into parts found in the base and parts found in the handset, given the changes in telephone design. It places more emphasis on installation of phone service in homes with burglar alarm systems because of the increased prevalence of these systems and the need for particular attention to wiring when an IP voice EMTA replaces a network interface device (NID) as the primary distribution point for telephone service. Speaking of the EMTA, the fundamentals of broadband telephony section has greatly expanded the topics related to that piece of equipment. The tech is expected to know about AC power and battery backup installation, as well as typical provisioning procedures, including number portability. Here’s where data knowledge overlaps telephony, since the EMTA is also a cable modem. Within the installation category, reference to the rulings on the deregulation and divestiture of AT&T and the Bell system (remember the network demarcation point?) have been replaced by the need to know the purpose of the Telecommunications Act of 1996 and the impact of Federal Communications Commission Part 68 requirements. The certified voice telephony installer is also expected to know the differences in categories of twisted-pair wiring, as well as the various color coding and connector positions associated with them. Finally, there’s a whole new set of tests and test equipment to be mastered for troubleshooting and maintenance proficiency. Knowing how to use the basic butt set, toner and meter are still requirements, but so are use of a quadrature amplitude modulation (QAM) analyzer and a voice quality tester. For help along these lines, take a look at the voice quality testing article on page 42. The outline also references Web-based tools performance verification. Many of these "tools" are really software that are also used to verify high-speed data operation. Anticipating some EMTA features expected to reach market in mid-2006, it also references loopback testing. Still evolving All this should point out that telephony, even at the installer level, is still an evolving field. Certification is one way to prove an installer tech is proficient in the latest technologies and installation procedures. SCTE certification with a voice endorsement is a benchmark that ensures consistent installation quality from both operators and contractors. Justin J. Junkus is president of KnowledgeLink and telephony editor for Communications Technology. Reach him at [email protected].