Date Added: Jan 2011
Modern Voice-over-IP (VoIP) communication systems provide a bundle of services to their users. These services range from the most basic voice-based services such as voice calls and voice mail to more advanced ones such as conferencing, voice mail-to-text, and online address books. Besides voice, modern VoIP systems provide video calls and video conferencing, presence, Instant Messaging (IM), and even desktop sharing services. These systems also let their users establish a voice, video, or a text session with devices in cellular, Public Switched Telephone Network (PSTN), or other VoIP networks.