Using SIP presence and availability in call routing

This article is a brief introduction about presence information in call centers in relation with Ozeki VoIP SIP SDK. After reading through this page you will be fully familiar with all the essential terms concerning SIP presence information in call centers and what you will need for creating your own solution using Ozeki VoIP SIP SDK.

What is SIP presence?

The call routing is the very basic function of a call center server that performs the distribution of the incoming calls between the call center clients. The call routing can be implemented in different ways according to the routing method you want to use.

Figure 1 - SIP presence in call routing

The basic problem of any call routing is that the server has to be able to decide if a call center client can receive a call or not. The simplest cause for not being able to receive a call is that the client is occupied with an existing conversation, but there can be other cases too.

The call center agent needs to be able to set their presence information to notify the server if they are able to receive a call. The presence information can specify if the agent is not at the computer at the precise moment and therefore they cannot answer a call.

It can be easily see that setting the presence information is a basic problem in call routing process.

Training guides, simple examples

If you would like to visit the detailed developer documentations, you can learn much more from the Ozeki VoIP SIP SDK Training chapter.


This article introduced you the basic knowledge about SIP presence information handling in call centers and showed how Ozeki VoIP SIP SDK can help you to fulfill your wishes about this topic. If you have read through this page carefully, you already have all the knowledge you need to start on your own solution.

As you are now familiar with all the terms concerning this topic, now it is time to take a step further and explore what other extraordinary solution Ozeki VoIP SIP SDK can provide to you.

If you have any questions or need assistance, please contact us at

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

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