If you are testing 25.01 on RL9 beware of this issue:
https://github.com/onrelay/sipxecs/issues/67We found over time the SIP transaction garbage collection stopped working, so eventually the number of active SIP transactions exceeds the max, causing 408 timeouts.
The issue has been diagnosed, and a fix is being tested for update 9. We will however just monitor for a couple of days before publishing to ensure no unexpected side effects.