<body> This package implements the main protocol abstractions that are defined by the SIP RFC 3261. These include the following main ones: <ul> <li>SIPServerTransaction -- an implementation of the Server Transaction State Machine (Chapter 17 of RFC 3261). <li>SIPClientTransaction -- an implementation of the Client Transction State Machine (Chapter 17 of RFC 3261). <li>SIPDialog -- an implementation of the SIP Dialog ( Chapter 11 of RFC 3261 ). </ul> SIPTransactionStack is the container that holds references to these protocol objects. </body>