In addition to the B2BUA-style applications developed in the ECharts language, it is often useful to compose SIP proxy applications to provide routing or other pre-connection application logic. We have supplied a special proxy servlet that works with the application router and provides logging capabilities that are consistent with other ECharts applications. This EChartsProxyServlet can be subclassed to provide application-specific logic. See the E4SS javadocs for more details.