A Case Study of Telephony Installation

This month, you’re going to join me as an observer at an actual voice over Internet protocol (VoIP) installation as it is videotaped for training use. I will provide a running commentary on procedures and the reasons they are being implemented, with apologies to ace Comcast technician "JD" Duncan if my memory isn’t as good as the video tapes we used. The scene is a nice neighborhood, on a street straight out of the Cleavers’ family album. The homes are single-family residences, all built sometime in the 1960s. Our job is to install digital telephony (a.k.a. VoIP) using a ported number, in a home that currently subscribes to video service only. It’s a recent move for the current owner, so there is no existing phone service. There is also an alarm system that must be connected to phone service. Before work begins The first tasks are nontechnical and not unique to digital telephony. JD parks the company van in front of the customer’s home, implementing the appropriate safety procedures by placing cones around the truck. He introduces himself to the customer, verifies the service changes, and explains to the customer what we will be doing. This professional approach cannot be overemphasized. Remember that cable is the new kid on the telephony block, and it doesn’t hurt to outshine the telco we are replacing. Checking the signal path The next task is to check both the physical state of the drop and RF signal levels. This is particularly critical for digital offerings, including digital telephony. Remember, we don’t get "snow" during a telephone call-we lose the call completely if signal level drops below acceptable levels. Our drop is not in the best condition. It had been converted from overhead to buried on the customer’s property; however, the tap remains overhead. The cable run up the pole forms a nice trellis for some type of vine, which exerts amazing pull on the service loop. (Does kudzu grow in Indiana?) Given the overall conditions, JD makes the decision to replace the drop to the home following good installation practices, which include proper bonding. Checking signal path inside the residence At the house, phone wires are terminated at a network interface device (NID). JD will later disconnect the house lines from the NID. First, he needs to inspect the house wiring, which enters in the basement, and the location the customer has chosen for the embedded multimedia terminal adapter (EMTA). Upon inspection, JD finds that the house telephony wiring is not up to the standard we need for digital service. Several extensions have been added over the years and have been spliced in a "rat’s nest," which makes it difficult to identify pairs to the various rooms. Fortunately, all the telephone wiring appears to be at least standard copper pair. (It is not unusual to find speaker wire and lamp cord in some homes.) JD replaces the splices with a connector block, which facilitates visual identification of pairs and allows easy changes in the future. This step would normally be done only after verifying existing dialtone at each phone outlet, but since there is no existing phone service, JD can disconnect the pair from the NID and rewire to the connector block now. Because of the alarm system, however, he will not connect the block directly to the EMTA. As this column discussed in July, he needs to connect the pair from the EMTA to the alarm RJ31x jack input side. The customer wants the EMTA to be located in an office on the second floor, where it will provide high-speed data service as well as telephony. Although there is a cable outlet in that room, the run is a combination of RG-6 and retail cable, with lots of splices. Furthermore, we are unsure of the quality of the telephone wiring to the room. Since the EMTA will replace the NID as it is the first connection for the entire house telephony wiring, JD decides to install new home runs for both telephony and cable to the EMTA from the alarm panel and drop, respectively. (My sympathy to all installers who work on new cable runs in attics during the summer.) The only splitter in the cable run is within a few feet of the drop entry, for all video service. Even though JD can’t verify existing dialtone at each jack in a home without telephony service, he could use a tone generator (toner) to verify continuity from the block to each phone outlet. However, since the customer has indicated that she would prefer most of the outlets at different locations, he makes the decision to bypass this step for now. Instead he now connects the output side of the RJ31x jack to the connector block input side. Then, he connects the telephony home run from the EMTA location to the input side of the RJ31x jack. Finally, he connects the cable drop to the cable home run to the EMTA location. With new cable and telephone wire in place to the EMTA, JD’s next step is to wire the cable and telephony jacks at the EMTA location. He then verifies that RF signal levels fall within range at the EMTA. Once this is completed, he builds and runs an electrically straight silver satin wire jumper between the EMTA and the telephony wall outlet. Activating service Activation consists of connecting the RF lead and AC power to the EMTA, verifying cable modem operation for data, and completing the final steps of provisioning and porting the telephone number. JD installs the backup battery in the EMTA and connects the RF terminal of the EMTA to the cable outlet. He then connects the AC power lead to a nonswitched wall outlet. To prevent accidental disconnection of service, the power plug is screw-secured to the wall plate. With power and RF connected, cable modem registration can be observed by watching light sequences on the EMTA. When registration is complete, JD calls the installation support line on his cell phone to complete the telephony provisioning and porting sequence. Depending upon back office automation and the MSO’s relationship with the incumbent telephony provider, this can take up to an hour. Comcast is in the process of automating this process to shorten the interval to minutes. Finally, JD verifies cable dialtone at all existing phone outlets and TV reception at cable outlets. The telephony verification includes checking each outlet for polarity of the tip and ring telephony leads, as well as for presence of dialtone. He corrects or tags any problems and schedules an appointment with the customer to complete installation of new jacks at the desired locations. All that remains is to discuss the new service and its features with the customer and confirm the appointment for new outlet placement. Although we have covered the lion’s share of a more difficult VoIP installation, a word of caution is in order to installers. As good as it is, this column is no substitute for formal training, which is available through your company, as well as from various training vendors. A good program will include a combination of VoIP theory, video scenarios, student workbook, and hands-on simulation. The Society of Cable Telecommunications Engineers is an excellent reference for sources. Justin J. Junkus is president of KnowledgeLink and telephony editor for Communications Technology. Reach him at [email protected].