SESSION DESCRIPTION IP based Telecommunication has revolutionized the way in which we communicate and conduct business. It is hoped that JSLEE (Java Service Logic Execution Environment) will unleash a major revolution in the Java IP Telecom services industry in the same way that the EJB specification revolutionized the application of Java to the Enterprise. The architecture and major programming concepts of the SLEE specification, different implementation choices that are allowed by the SLEE specification, and the ongoing implementation of SLEE on the JBOSS platform as part of the Mobicents open source telephony platform will be described.