Print this page Introduction to Digital Telephone and VOIP
Thomas Mason, PE
Course Outline
The 3-PDH course begins with a discussion of the various hardware components which must be selected - instruments, office wiring, data switches, the digital telephone box, central office circuits and essential special hardware features. The second main topic is reliability, which should be driving requirement of the final selection. The third main topic is features, costs, automatic fail-over, failure-mode operation, automated attendant, call director, voice-mail, hold, call-waiting, conferencing, call forwarding, group pickup, remote access and remote monitoring and maintenance, quality of service and contract support. The final section is vendor contact information.
The course includes
a multiple-choice quiz at the end, which is designed to enhance the understanding
of the course materials.
Upon completion of this course, the student will be able to:
- technically describe LAN wiring;
- distinguish LAN-compatible telephone wiring from non-LAN-compatible;
- distinguish standard telephone instrument features from optional features;
- compare “wall warts” with POE telephone instrument power;
- explain how multi-line service is provided via single electrical circuit;
- explain analog telephone and how it evolved into digital telephone;
- distinguish between premises-switching and central office-switching;
- estimate the external bandwidth required for premises-switching and central office-switching;
- identify critical hardware requirements for essential failure-mode operational;
- identify digital telephone system failure modes;
- identify digital telephone fail-over capabilities;
- identify single-point failure modes;
- provide price brackets for different digital telephone architectures; and
- provide price brackets for on-premises vs central office digital telephone systems.
Intended Audience
This course is intended for electrical designers and project managers who are responsible for providing digital telephone infrastructures (wiring systems and rack capacities) before the system selection has been made.
Benefit to Attendees
It is valuable for technically-oriented persons interested in understanding how the increasingly complex world around them functions.
Course Introduction
Oral communications are essential to our business and personal lives. In all cases, a project scope of work results from interactions between persons who recognize a need and people with access to resources to satisfy the need. As the project moves to contracts and construction documents, more and more information must be communicated between the users, the designers and the vendors. We tend to focus on the latest stages of construction documents, the specifications, construction drawings and contracts, which end up on paper. This course, however, focuses on the oral communications channel which makes up much of the early stages of project definition but continues though detailed design, construction and commissioning. We will examine digital telephone and VOIP because every business in America has already made a decision on the system they use but are today being asked to re-think that decision for commercial and economic reasons. This course will help in such re-examination of needs, equipment and service choices.
Course Content
In this lesson, you are required to download and study the following course content:
Introduction to Digital Telephone and VOIP
Please click on the above underlined hypertext to view, download or print the document for your study. Because of the large file size, we recommend that you first save the file to your computer by right clicking the mouse and choosing "Save Target As ...", and then open the file in Adobe Acrobat Reader. If you still experience any difficulty in downloading or opening this file, you may need to close some applications or reboot your computer to free up some memory.
Course Summary
This course has stated that all telephone systems presently in use are digital - even when the voice signal from the handset to the central office is analog, the DTMF tone dialing and out-of-band control signals are digital. This “conventional” telephone service is purchased from a local telephone company, but similar and more advanced services can be purchased on a capital basis or monthly basis from a range of suppliers. Maintenance of instruments, wiring, the digital telephone box and out-going connections can be individually handled in-house or contracted out.
The course recommended that Cat 6 LAN cable be used for digital telephone because of a 20-year expected life. We recommended that conventional business procurement analysis be applied to the selection of in-house vs contracted-out services and the location chosen for the telephone box. The consequences of these decisions are vital to the firm - quality of service provided internally and to Clients and the competitive benefit of reliability of operation.
The basic purchase decisions are on-premises telephone box or remote telephone box (hosted service) and how much service is to be contracted vs. in-house. For reference purposes only, an expired quote for a 25-phone commercial system is included. They want $1400 up front and $700 per month, or $30 per phone per month. Another vendor promises (in writing) $20 per-phone-per-month. Your actual costs may vary.
Related Links and References
For additional technical information related to this subject, please visit the following websites or web pages:
http://en.wikipedia.com/wiki/Telephone
http://en.wikipedia.com/wiki/Carterphone
http://www.silicon.com/white-papers/view/network-technologies/ip-telephony-from-a-to-z-60289634/
http://www.business-analysis-made-easy.com/Example-Of-A-Decision-Matrix.html
http://www.eventhelix.com/realtimemantra/faulthandling/system_reliability_availability.htm
http://whatis.techtarget.com/definition/0,,sid9_gci213915,00.html (DSL)
Quiz
Once you finish studying the above course content, you need to take a quiz to obtain the PDH credits.
DISCLAIMER: The materials contained in the online course are not intended as a representation or warranty on the part of PDH Center or any other person/organization named herein. The materials are for general information only. They are not a substitute for competent professional advice. Application of this information to a specific project should be reviewed by a registered architect and/or professional engineer/surveyor. Anyone making use of the information set forth herein does so at their own risk and assumes any and all resulting liability arising therefrom.
