Succeed doing a local voice intercom with Olimex esp32-poe-iso(lx6) as primary and ESP32-S3-DevKit-Lipo(lx7) as DSP with ECHO cancellation . The voice communication is full duplex. Initially tried without the lx7 and was impossible to make a full duplex communication due to big noise echo. So, lx7 is doing a good job in canceling the echo.