VoIP or Voice over Internet Protocol is a technology that handles the routing of voice conversations over an IP network, such as the internet.
Using voice over IP requires the use of both hardware and software for users to send their voice as a digital signal over the internet, instead of over traditional PSTN networks provided by telecom providers.
Popular services such as the Gizmo Project and Skype run a software client on the computer to enable calls to be made over the network, for example, using a sound card and headset.
Voice over IP technology can potentially offer savings because a single network is used to deliver voice and data traffic over an IP network. Voice data is sent in packets using rather than by traditional POTS circuits.
Users who have existing under-utilised network capacity can then carry VoIP with no extra charge . VoIP calls over the internet generally do not incur a charge beyond what the user is paying their ISP for internet connectivity.
Reliability of voice over IP technology in business can also be compromised by power outages.
Closely linked with VoIP, some companies are considering using the IP Multimedia subsystem (IMS) to bring together mobile applications which use VoIP. The prevalence of IMS would allow uses to upgrade their existing IT infrastructure while also linking web technologies including email, video conferencing and presence information. This would allow existing VoIP systems to interface with PSTN networks and mobile phones.
The two major competing standards for VoIP are the IETF standard Session Initiation Protocol (SIP) and the ITU standard H.323. Recently however, H.323 has since been surpassed by SIP.
Recent CW articles on VoIP
This was first published in August 2007