IP PBX: How an IP PBX/VoIP Phone System works

The IP PBX/ VoIP Phone System includes the following components:

• one or more SIP/VoIP Phones
• IP PBX server
• VoIP Gateway (optional)

The IP PBX server is similar to a Proxy server. It is such a server that forwards the requests of clients to other servers. SIP clients can be hardware of software phones. These connect to the IP PBX server and they send a request to the IP PBX when they want to initiate a call, and the IP PBX creates the connection. The server contains the data of all the telephones and users with their SIP addresses, and that is how it can execute external and internal calls with the help of the VoIP Gateway or the VoIP porvider.

Figure 1 - An example for integrating the PBX into a network

Related pages:

• An example of a SIP call session between two phones
• Information about VoIP Gateway
• VoIP definitions
• Different Types of Codecs and their use