What is this VoIP? This is just IP Telephony also known as Internet telephony or Voice over Broadband. This is real telephone of future. Using your high-speed Internet connection you can make all your phone calls with having the cost advantages to consumers over traditional telephone networks. Besides that you get the ability to transmit more than one telephone call down the same broadband-connected telephone line. Therefore VoIP is real great idea for a simple way to add an extra telephone line to a home or office. Most of the difficulties of creating a secure phone over traditional phone lines, like digitizing and digital transmission are already in place with VoIP. It is only necessary to encrypt and authenticate the existing data stream. 3-way calling, call forwarding, automatic redial, and caller ID; features that traditional telecommunication companies normally charge extra for.

Secure calls using standardized protocols (such as Secure Real-time Transport Protocol.) Most of the difficulties of creating a secure phone over traditional phone lines, like digitizing and digital transmission are already in place with VoIP. It is only necessary to encrypt and authenticate the existing data stream. You get integration with other services available over the Internet, including video conversation, message or data file exchange in parallel with the conversation, audio conferencing, managing address books, and passing information about whether others (e.g. friends or colleagues) are available online to interested parties.
VoIP gives the ability to be mobile. One can make international calls to be in contact anytime, anywhere with an internet connection.
So, one has all reasons now to start to use VoIP. I hope people involved in this project taking care of the future compatibility, security and reliability issue of the exchanges.