Add to ORKGMaster’s thesis is trying to create opensource IM application for communication in Jabber network. In nowadays it is getting more and more popularity as at providers, so mainly at end users. In first half of thesis are explained basics of whole issues and in second half is described resulting application, which has been created by using of object oriented programming language Java. Java is very extended between programmers for her simplicity and great support. Thanks this is available a many external libraries and extensions. Application has been written on Smack library in version 3.04 and VoIP module on JMF (Java Media Framework). Graphic interface has been created by using of standard Java visual components (javax.swing)