How to detect power outage ?

[Jeroen Bartels]

But without power there is no connectivity and I would want to be notified for for no connectivity too. Both ways action is required. And cheaper than UPS solutions.

[Digit]

OTOH, absence of a UPS can be expensive as well

[AshaiRey]

But without power there is no connectivity and I would want to be notified for for no connectivity too. Both ways action is required. And cheaper than UPS solutions.

Without connectivity there still can be power
And when someone else has no connectivity to your system that doesn't mean automatically that your system lost connectivity too.
This methode is very lean to trust on.

Have a look how a security system handles this problem when a power outage occure.
It's often done with a small battery pack and a short call to a mobile or landline.