PBX systems

This article introduces PBX systems, and by reading through this page you will be fully familiar with all the essential terms concerning PBX. It also introduces what you will need for creating your own PBX in C#, using Ozeki VoIP SIP SDK.

What is PBX

The Private Branch Exchange is a server application or a physical device that is used for phone line establishment between two VoIP clients using the SIP (Session Initiation Protocol). The PBX uses so-called SIP accounts for registering the SIP clients to the server and establishes communication lines between the SIP clients through standard SIP messages.

voip pbx systems
Figure 1 - VoIP PBX Systems

The software PBX is a special application that is used for sending, receiving, parsing and creating SIP messages. The SIP messages can be categorized according to the sender or the type of the messages. In one classification we can talk about Client and Server messages and in an orthogonal classification, there are INVITE and Non-INVITE messages. These two classifications can be combined, therefore we can distinguish 4 basic SIP message types.

The PBX System role is to work with the SIP messages, manage the client registration via SIP accounts, establish and terminate SIP communication lines. The PBX you will be able to build with Ozeki VoIP SIP SDK needs to be able to handle the SIP messages properly and have all the program support (codecs, protocols) for the SIP communication.

PBX implementation

Ozeki VoIP SIP SDK provides namespaces specialized for PBX development. You can create working PBXes with default functions by adding only a few new lines into your project. It's also simple to customize your PBX, since the SDK provides the necessary methods and background support for this purpose.

Examples on PBX implementation:


This article introduced you the basic knowledge about PBX systems and showed how Ozeki VoIP SIP SDK can help you to fulfill your wishes about this topic. With the usage of the SDK you can develop PBXes with various functionalities easily and fastly.

If you have any questions or need assistance, please contact us at info@voip-sip-sdk.com

Select a suitable Ozeki VoIP SIP SDK license for your project at: Pricing and licensing information

Related Pages

After you've read through this topic, you should be familiar with PBX implementation. To learn more about the the opportunities provided by Ozeki VoIP SIP SDK, please continue your study with the following examples: