Hello Pablo,
Someone tested echo on sems ? How I need to configure sems.conf to test echo ?
You don't need to configure anything for the echo plug-in. All you need to configure is Ser (ser.cfg) to redirect some number or special URI to the echo module. You can find an example with 'voicemail' at <ser>/examples/voicemail.cfg. Then, you just have to replace 'voicemail' with 'echo', so that any call gets redirected to echo.
-Raphael.