Description

Ozeki VoIP SIP SDK provides a first-rate technology for softphone development. Instead of wasting time for long development process on your own, you can take advantage on this decent software development kit. You will see how easy it is to create a softphone when you use Ozeki SIP SDK. A basic programming knowledge is enough, since Ozeki SIP SDK provides the base for the VoIP solution you are working on.

On the pages below you will find all the information you need to build your own softphone. You can learn how to develop softphones on basic and advanced level, how to handle calls with the implemented softphone, how to customize the softphone GUI, etc. The various codecs and clients are also explored. The journey to softphone development is starting right ahead.

This example demonstrates how to implement the sip invite method in c#. The INVITE SIP method indicates that a client is being invited to participate in a call session. To use this example, you need to have Ozeki VoIP SIP SDK installed, and a reference to ozeki.dll should be added to your visual studio project. It's also recommended to visit the SIP REGISTER article before you begin to study how to perform SIP INVITE.

What is a SIP INVITE method? When is it needed?

The INVITE is a SIP method that specifies the action that the requester (Calling Party) wants the server (Called Party) to take. The INVITE message contains a number of header fields. Header fields are named attributes that provide additional information about a message. The ones present in an INVITE include a unique identifier for the call, the destination address, Calling Party Address, information about supported codecs, and more information about the type of session that the requester wishes to establish with the server.

Sip invite is being explained by an example as well, as you can see on Figure 1; from Ozeki VoIP SIP SDK an INVITE request is being sent through a PBX, to a Softphone. A "101 Trying" message is being sent back, and if the request has reached the destination, a "180 Ringing" message is going to indicate that the softphone is ringing. When the session is being established, a "200 OK" message is being sent to the caller, which than sends back an "ACK" message to confirm it received the final response to the INVITE request.

How to implement SIP INVITE method using C#?

To perform the SIP INVITE task in C# using Ozeki VoIP SIP SDK, you need to implement the register process, than you need to use the IPhoneCall interface to create a call as an object, subscribe to its CallStateChanged and CallErrorOccured events to get notified about the call's state, and make the call by calling the object's Start() method (see sip invite example below).

Additional Information