My UPS died over the weekend that unfortunately has the backbone switch, switch failure cascaded to the firewall locking it up too; meaning my alerts didn't go out either. What out-of-band methods do you use to ensure critical notifications are received?
Note: we only have one ISP so a backup ISP isn't a solution (yeah small town) and no my switch isn't dual power supplied (none are). The UPS was tested Q1 and reported no issues, it's not a battery failure, the entire unit is dead.
tldr; cascade of issues prevented critical notification of hardware failure of UPS. How do you overcome?