Background on IP Telephony & VoIP
IPT (IP Telephony) & VoIP (Voice over Internet Protocol) allow users to make and receive phone calls using the Internet Protocol to transmit speech and help integrate voice and data applications.

In recent years IP Telephony was positioned as an efficient, low cost technology which offered an opportunity to bypass the regulated Telephony industry infrastructure. The service quality was not always on par with the traditional telephone experience. Nevertheless IPT's promise helped build significant pressure on the traditional telecom sector and has resulted in substantial rate reductions.

Positioning IPT on price alone does not do it justice. IPT offers many powerful features and capabilities. Today's advocates correctly position IPT and other RTC (Real Time Communication) applications as productivity enhancing applications for knowledge workers.

The applications: Voice is one of Microsoft's premier RTC applications featured within its new .NET services suite. Other RTC applications include IM/text chat, application sharing, remote assistance, Voice and Video.

IPT Features & Capabilities:
Unified Messaging
Receive your voicemail either by e-mail or call in as usual to retrieve your messages. When you are unavailable calls may be forwarded to another number or go to voicemail.
Phone Number for Life, Travel/Roaming-
Whenever you log in on the Internet to get e-mail, you tell the network to which station to send the mail. This same registration can be used to indicate where you would like to receive calls. Your IP phone number travels with you, wherever you are in the world, as soon as you log into the Internet. This is a tremendous advantage for those who travel frequently or are mobile workers. It means you can keep your phone number for life, no matter where you move to, just like your e-mail.
Integration with Instant Messaging
Instant messaging is a tool used heavily by today's youth and is also increasingly used in the corporate environment. One of the great features of IM is Presence Management: The ability to see instantly who is online and available for an IM session. Besides typing with the person you can also choose to speak with the person on your buddy list. Today these calls are totally free. No matter if your conversation partner lives next door or at the other end of the globe. These are truly some amazing features unavailable to the average user until today. Since the cost of the IP telephony subscriptions is low, one could set up multiple accounts one for each member of the family. No more annoying phone calls to answer for your teenagers. As the responsible adult however, you can still be in charge.
Administration & Control
As the administrator you could set controls such that all calls for your teenagers are forwarded to voicemail between 10PM and 7AM. You could also set that your teenagers may only receive calls from the people listed in your (Outlook) phonebook or you could set the system to automatically record certain calls. The administrator can access call logs for calls placed and received, and listen to all messages if needed and much more.
Replaces your POTS line!
Voice service does not use much bandwidth and can work on a dial-up line. Voice service works best with a high speed Internet connection like a cable modem, a DSL connection or even a dedicated T1 line. With any of these services you can run multiple phone lines at any time, browse the internet and do everything else you want to do online. For service providers this is a good service which helps prepares customers for more bandwidth hungry applications like streaming media or video conferencing.
Voice activated dialing
Today's consumer PC is a powerful machine, with more than 1 Gigahertz of processing capacity. Voice recognition technology has come a long way in recent years.
Remote control of PC
Similarly you could tell your PC to do other things like e-mail that schedule to all members of your soccer team. Or turn on the air-conditioning in the den etcetera.
One Wire (LAN/Ethernet) for Voice and Data
One wire simplifies new construction and reduces costs. Real cost savings are also realized through reduced maintenance when performing moves adds and changes to the business communications system.
Application Integration
Information systems, CRM financial control project and customer management etc. etc. Ability to record transactions and file the audio files with other customer documentation
(Distributed) Contact Centers
With today's broadband proliferation call centers can take advantage of distributed call center capabilities. Students, Homemakers and part-time professionals can log-on and be ‘on-call’ from their home-office or remote locations.