How Voip Works
At its most basic, VoIP needs an Internet connection and some way of converting sound -- in this case voice -- to a format computers can understand.
The first VoIP calls were computer to computer connections. Several VoIP services still support these so-called "soft phones", for example as a way for laptop users to make calls when they are out of the office. But most VoIP users now either use a dedicated Internet phone or a hardware adapter that connects up conventional handsets. It is also possible to integrate VoIP to office phone systems.
In each case, the hardware or software converts speech into data, transports it across the Internet, and converts it back into speech for a conversation. In addition, most VoIP services now have their own phone switches to allow VoIP users to call non-VoIP phones.
As the Internet was never designed for real-time communications such as voice, VoIP uses a series of inter-dependent protocols to work effectively.
Most VoIP services use a transport layer called User Datagram Protocol (UDP) and an application layer called Real-time Transmission Protocol (RTP). Internet data doesn't always arrive in the order it was sent, so RTP puts the data in the right order before it is converted back to speech.
The protocols also allow fragments of data to be ignored if they do not arrive quickly enough to ensure a smooth conversation. Ignoring data like this is rarely an issue as there is usually enough information coming through to make the conversation perfectly audible. The faster the broadband connections of both callers the less likely this is to happen.
