Switching to VoIP

More and more businesses today have their receive phone service

through Internet instead of local phone company lines. Many

businesses are also using their internal local and wide-area

network infrastructure to replace legacy enterprise telephone

networks. This migration to a single network carrying voice and

data is called convergence, and it's revolutionizing the world of

telecommunications by slashing costs and empowering users. The

technology of families driving this convergence is called VoIP, or

Voice over IP.

VoIP has advanced Internet-based telephony a viable solution,

piquing the interest of companies small and large. The primary

reason for migrating to VoIP is cost, as it equalizes the costs of

long distance calls, local calls, and e- mails to fractions of a

penny per use. But the real enterprise turn -on is how VoIP empowers

businesses to mold and customize telecom and datacom solutions

using a single, cohesive networking platform. These business

drivers are so compelling that legacy telephony is going the way of

the dinosaur, yielding to Voice over IP as the dominant enterprise

communications paradigm.

Developed from real-world experience by a senior developer,

O'Reilly's Switching to VoIP provides solutions for the most

common VoIP migration challenges. So if you're a network

professional who is migrating from a traditional telephony system

to a modern, feature-rich network, this book is a must-have . You'll

discover the strengths and weaknesses of circuit-switched and

packet-switched networks, how VoIP systems impact network

infrastructure, as well as solutions for common challenges involved

with IP voice migrations. Among the challenges discussed and

projects presented:

• building a softPBX

• configuring IP phones

• ensuring quality of service

• scalability

• standards-compliance

• topological considerations

• coordinating a complete system ?switchover?

• migrating applications like voicemail and directory

  services

• retro-interfacing to traditional telephony

• supporting mobile users

• security and survivability

• dealing with the challenges of NAT

To help you grasp the core principles at work, Switching to

VoIP uses a combination of strategy and hands-on "how-to" that

introduce VoIP routers and media gateways, various makes of IP

telephone equipment, legacy analog phones, IPTables and Linux

firewalls, and the Asterisk open source PBX software by Digium.

You'll learn how to build an IP-based or legacy-compatible phone

system and voicemail system complete with e-mail integration while

becoming familiar with VoIP protocols and devices. Switching to

VoIP remains vendor-neutral and advocates standards, not

brands. Some of the standards explored include:

• SIP

• H.323, SCCP, and IAX

• Voice codecs

• 802.3af

• Type of Service, IP precedence, DiffServ, and RSVP

• 802.1a/b/g WLAN

If VoIP has your attention, like so many others, then Switching

to VoIP will help you build your own system, install it, and begin

making calls. It's the only thing left between you and a modern

telecom network.