telecommunications training, dvd video courses, online telecom course, IP networking and MPLS training, VoIP fundamentals, books, certification

Teracom Tutorial: VoIP over Cable or DSL:
Telephone Service over Cable Modem

Go to Teracom home page scheduled public seminars, instructor-led telecom training, networking training, telecommunications training, VoIP training, MPLS training courses self-paced DVD video courses telecom, datacom, networking, IP, MPLS, wireless, training, learning, courses, online online certification and testing info on bringing any Teracom seminar to your location for a private team training session telecommunications training book, networking book Free online tutorials (graphic/text and VideoTutorials), plus knowledge evaluation quizzes, archived newsletter articles and more!
site map
 QUICK LINKS
Register for Certification
Register: Online Courses
Register for a Seminar
Order DVDs
Order Books
Certification Exams
Online Course Previews
Video Previews
Newsletter
CPE Credits
Specials
free bonuses - certification and online courses
 LEARNING YOUR WAY
Online Courses
Certification
Instructor-Led Courses
Private Onsite Training
DVD-Video Courses
Reference Books
Free Tutorials
 TERACOM
Why take our courses
Who will benefit
Value pricing
Reviews
Instructors
About Teracom
Contact us
Policies and FAQs
be notified of new tutorials, seminars, video releases and more
Teracom Tutorial: VoIP over Cable or DSL:
Telephone Service over Cable Modem

Note: This is an archived article that appeared in the Teracom newsletter January 2004, and this article has not been updated to reflect technology developments since then. But reading it, we think you will agree that in hindsight, this analysis written in 2004 is highly accurate... and gives you a good idea of the quality and durability of Teracom's training courses.

Please be assured that our training courses have been updated since the time of this article!

Subscribe to the free monthly Teracom newsletter
 

1.07  Voice over DSL/Cable
 
Local and long-distance voice
User: VoIP over Cable or DSL
ISP: Access network in metro area
IXC: Internet or managed IP network
Gateway to standard telephony at far end
Requires adapter at customer premise
Packetizes voice
Negotiates with call management servers
Cheaper
Bypass the LEC at origination
Bypass the regulators: “Internet” telephony
More efficient use of LD trunks
 
Voice over IP over cable modem or DSL broadband internet access has started to become mainstream. This is essentially an initiative by the cable companies to move into the telephony business – which forces the incumbent telephone companies to follow suit lest they lose a large chunk of their business.
This service supports Plain Ordinary Telephone Service (POTS) at both ends. At the originating end, the user must have an adapter into which they plug their regular phone and their computer. This adapter in turn connects to the cable or DSL modem, which links the user to the Internet Service Provider's access network in the metropolitan area. The ISP's access network is connected to the Local Exchange Carrier (LEC) to terminate local phone calls, and to an IP network for long distance.
In theory, the “long-distance IP network” is the Internet. If you are getting phone service from your cable company or from your phone company, this is unlikely, due to the total lack of Quality of Service (QoS) guarantees on the Internet and resulting total lack of guaranteed voice quality. It is much more likely that the calls will be carried over a managed IP network, which uses the same protocols as the Internet, but where the traffic, loading and quality are carefully controlled. The main tool for guaranteeing service levels is called MPLS.
If you are getting phone service from a third party, such as Vonage or Eric's Fly-By-Night Internet Phone Service, then the voice packets may well be delivered along with Internet traffic, where the service level is not guaranteed. It will probably be good. Maybe not.
It is even possible that initially, the VoIP calls will be converted at the earliest opportunity to regular telephony and carried long-distance like any other telephone call. This would be the simplest and cheapest way to guarantee voice quality.
The IP network will have to provide a number of services, including Authorization, Accounting and Administration (AAA), call management features and gateways to convert the IP telephony to standard telephony for the far end.
This type of residential telephony is cheaper than POTS for a number of reasons:
First, the switched access charges added by the LEC to any long-distance phone call are avoided.
Second, this service is being portrayed by the carriers as “Internet” telephony, avoiding regulation and fees imposed on POTS. Third, if variable-rate codecs are used, i.e. no packets are transmitted if no noise is coming out of the speaker's face, the long-distance trunk circuits are used more efficiently, thus costing less to the carrier.
This last point is the least important, as the wholesale cost of long-distance capacity is very close to zero due to recent technology-based exponential increases in capacity.
There are several hidden drawbacks to this scenario… discussed in Chapter 2 of Course 120.
Source: Teracom Course 130, Voice over IP, SIP, Security, 5G and the Internet of Everything , slide 1.07
online telecom training courses
online courses
telecommunications certification
certification
instructor-led course 101: telecom, datacom and networking for non-engineering professionals
instructor-led
seminars
textbooks, reference books, certification study guides
books
DVD video courses
DVD-video courses
boot camp
mind the gap!
tell a friend:
Join our satisfied customers including:
at&t verizon bell canada microsoft intel cisco gsa cox cable
 
Copyright © Teracom Training Institute.   All rights reserved.    privacy policy    contact us    FAQs, help and policies