Voice Over IP Architecture,Softswitch: Architecture for VoIP (Professional Telecom)

Book Title:	Softswitch: Architecture for VoIP (Professional Telecom)
Author:	Frank Ohrtman
Publication:	McGraw-Hill 2002
ISBN:	0071409777

Interactive communication has long been done over the telephone, since other means were either too expensive or too impractical, and restricted to either the military or the large corporations. The Internet solved some problems, when it made cross-continental communication easier and more inexpensive, and high-speed lines became suited for both live audio and video feeds.

The integration of the telephone system with computers and the internet has brought about some interesting possibilities, one of them being VoIP, (Voice over IP), which promises great distance conversation at low cost and all the benefits of using computers to aid the communication.

Thus, VoIP is about digitizing the voice signal, compressing it to suitable formats, transporting it as data packets over the existing Internet infrastructure and reverting it to analog at the destination, practically making possible cross-continental conversation at up to 70% less cost, and benefiting from compression, encryption, conferencing, simultaneous exchange of multimedia files to aid the conversation and so on.
However, there are tradeoffs in quality of service that must be considered when deploying a VoIP solution, due to the way packets of data are routed around the Internet. Since verbal communication must be a real-time process, efforts have been made to modify the conditions, using tricks and policies that affect the flow of voice packets in all routers along the way. Such policies include special fields in the IP protocol, packet queuing methods like First In First Out, Weighted Fair Queuing, Priority Queuing and so on, fixing the bandwith and Congestion Avoidance (i.e. Random Early Detection). These have been implemented in some way or another in the solutions different companies are offering, but using VoIP is still far from the ease of using a phone.

Softswitch : Architecture for VoIP (Professional Telecom) deals with alternative ways to accomplish packet data routing – at least for VoIP purposes – using software solutions. Softswitch are software products that work towards the same goal as expensive hardware one may find in the corporate VoIP systems. The book is technical, written for the network administrators, but it has an economic perspective as well, discussing the advantages of VoIP and demystifying softswitch technology such as Class 4 and 5 Replacement, IP Centrex, and IP-PBX. It shows how these can help companies provide VoIP Service with less than the cost associated with the more expensive hardware products that the traditional switch makers are proposing, and why, if softswitches are aided by SIP, they can support the Internet technologies existing today, so much as to replace the old fashioned telephone systems.

Softswitch : Architecture for VoIP has in-depth information about Quality of Service, the reliability and scalability of VoIP systems, arguing for a replacement for the classical PSTN phone lines by an "all-IP" network.

The book is comprised by 359 pages of technical information combined with an analysis of current trends and of the future market that make it suited for both network admins and managers, be them specialists with years of experience in the softswitch technology world or newbies.

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