A couple days ago I was wondering why our monitoring team did not receive any alerts about an outage. The problem was: one of our SBCs became unavailable for the Skype for Business environment, so the following events are generated:

So, the environment has recognised successfully the unavailable SBC, because there were no response for the SIP OPTION messages (Event 25051) and finally generated the 25061 event ID which means there were a major failure, because the failed OPTION messages has recorded 5 times in a row.

This led me to check the corresponding SCOM rules in the official Skype for Business SCOM Management Pack and I was surprised when I realised just the following events are collected and monitored by the SCOM for the Mediation Server role:

After all, I would recommend to everybody to create custom monitoring rules in SCOM to have the really important Events (especially 25061) monitored!