Core Electronics. Women Bottom Wear Top Wear. Top Wear Bottom Wear. Perpherals Mouse Pen Drives. Chargers Screen Guards. Product was successfully added to your shopping cart. Availability: In stock Regular Price: Rs. Description Additional Tags Reviews. Details Product Summary This book offers a comprehensive overview of the issues to solve in order to deploy global revenue-generating effective ""multimedia"" services. Product Tags Add Your Tags:. Be the first to review this product. Write Your Own Review How do you rate this product? Submit Review. Voice coding technology is also presented as a black box, with enough information for an engineer who wants to use an existing coder in an application, but without describing the technology in detail.
IP Telephony will be useful mainly in the lab development platforms, validation platforms , when designing and troubleshooting new interactive multimedia applications. The companion book Beyond VoIP Protocols becomes necessary when you deploy these applications in the field, over a real network with limited capacity. Beyond VoIP protocols contains an overview of the techniques that can be used to provide custom levels of quality of service for IP data flows, and guidelines to properly dimension an IP network for voice.
It also delves into the details of voice coding technology, and the influence of the selected voice coder and the transmission channel parameters on perceived voice quality. Although reading the standards is always necessary at some point, these documents were never written to be read from A to Z. Not only the mere volume is a problem, hundreds of pages for each standard, but also the structure is inappropriate: all VoIP standards are written as umbrella documents, which point explicitly or implicitly to dozens of other more detailed documents.
Sometimes, these documents are also misleading, because some of the recommended methods were discussed in a specific context 2 Tromboning refers to a non-optimal media path through the network, compared to the shortest path. It happens when the media streams have to zigzag across multiple nodes, reminding of the shape of a bent trombone. Last but not least most standards are the result of diplomatic agreements between firms, which often results in multiple alternate ways of doing the same thing, very long and cumbersome documents with many options and unclear sentences designed to preserve the agreed compromise, while in practice after a few years, the market forces lead to a de-facto standard choice, in general adopted from the practice of the dominant players.
We wrote IP Telephony because we believe it is much more efficient to gain first a general overview on VoIP, and only then go into the details of the standard documents, but only when needed and if clarification is required on a specific item.
IP Telephony: Deploying Voice-Over-IP Protocols
IP telephony begins by giving an overview of the techniques that can be used to encode media streams and transmit them over an IP network chapter 1. If focuses on the functional requirement of transmitting an isochronous data stream over an asynchronous network which introduces delay variations jitter. The media encoding methods themselves are presented very briefly, with just enough details for an engineer who wants to use them and understand the main parameters required for the transmission of the resulting data. The most popular VoIP standards are presented in chapter 2 H.
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These chapters do not intend to fully replace the standards, but provide a detailed overview that should be sufficient for most engineers and pointers to relevant normative documents if further reference is required. The value of these chapters comes also from the many discussions on aspects of the standards that are still immature, and descriptions of calls flows or protocol extensions commonly used by vendors but not described in standard documents.
The advanced topics chapters chapter 5 and 6 , discusses two issues faced by all service providers when deploying public VoIP services as opposed to custom services designed for a single enterprise. The first issue comes from the incompatibility of current VoIP protocols with Network Address Translation routers and firewalls, which change the addresses of IP packets on the fly but without properly translating the IP addresses contained in the VoIP messages carried by these packets.
The second issue comes from the widespread confusion between private telephony techniques and public telephony techniques for call transfers. In both cases the chapter presents techniques that were deployed successfully, and explains the pros and cons of each possible method. As we were writing this book called IP Telephony: DeployingVoice-over-IP Protocols, it was of course very difficult to ignore the protocol wars which seem unavoidable. The exercise was made especially difficult by the telecom bubble, during which it seems many manufacturers and many service providers forgot that telecommunications is a science, and more and more strategic or even technical decisions have been made based on misleading marketing campaigns.
For instance UMTS interactive multimedia applications are always presented as all IP based, while in fact they are all circuit based 3, and for fundamental technical reasons that will last for years! This is a very big problem for the telecom industry as a whole, because too many manufacturers or service providers have started to digest and believe their own overinflated marketing, and this vicious circle leads to inordinate amounts of investment money that will not survive the reality check of deployments.
We have seen so many concept companies grow with the bubble, and then fail. Even large companies are still investing massively in programs that sometime seem a bit surrealist and are obviously poised for failure. As the CEO of one of the largest service providers put it in a recent press conference: it is high time for us to become a company of engineers again. There is little a book can do to help sanitize the world of VoIP, but we have tried to discuss openly the pros and cons of each protocol, each time with specific arguments and suggestions for improvements.
Our opinion is that all of the protocols described have a future, and each has some unique characteristics that make it unavoidable for the next 5 years: H. In addition, H. All pending problems of the protocol have been solved as the protocol matured. However it is weak for PC applications. SIP undoubtedly benefits from the biggest marketing momentum.
However, as we have seen above, it is important to distinguish between marketing and facts.
SIP is an excellent choice for PC centric applications: as a UDP based protocol it is relatively easy to get it to work across Network Address Translation devices, which facilitates the deployment of VoIP services independent of the underlying network provider. IP based protocols, which introduce an error multiplication effect because a single bit error kills the whole packet, cannot be used on current radio links for interactive media. The most efficient work so far has been done by the 3GPP consortium, which is in fact almost redefining its own version of SIP.
MGCP has quietly become one of the most successful protocols, both in core networks where it serves to control trunking gateways, and at the edge to control business IP phones where it has unparalleled features for screen and function key control , and analogue lines only MGCP allows full transparency with existing PSTN features. The protocol had by far the best design quality upfront, and there are very few things to fix in the latest version of MGCP. We often had the request to describe in details H. We decided to not cover it in this edition, as we do not believe H.
The concept of the protocol is simple: it is a form of tunneling. VoIP now makes the front page of major economic newspapers that describe it as a technology that will reshape the telecom industry. We hope that this momentum will remain reasonable and will not end up in a new bubble.
VoIP does have major advantages and offers a potential for new disruptive business models, but this comes with the challenges of any new, relatively immature, technology. If we have achieved our goal, our readers will be able to perform a thorough reality check on any elaborate marketing story, and enjoy the benefits of VoIP while avoiding the pitfalls. Andreas Steffen A. Steffen, Carle, Dr. Georg Carle Dr.
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Thomas Fuhrmann. Introduction This 4-day course offers a practical introduction to 'hands on' VoIP engineering. Voice over IP promises to reduce your telephony costs and provides unique opportunities for integrating voice. Why SIP? During this 3-day course delegates will examine SIP technology and architecture and learn how a functioning VoIP service can be established.
Introduction 2. QoS in VoIP 3. H 4. Signalling in VoIP 5. Conclusions 2 1. Introduction to VoIP Voice.
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International Marketing Research Third edition C. Components of. Configuring H. Real time voice and video communications among multiple participants The past Channelized, Expensive H. Introduction Understanding Voice over IP For years, many different data networking protocols have existed, but now, data communications has firmly found its home in the form of IP, the Internet Protocol.