Mobile request

Hello, could it be possible for the mobile phone application to try to communicate with the home assistant if it is not available. This could be useful for several things, one of which is the alarm at home, if the power goes out the cell phone tries to communicate for x minutes if it doesn’t work, let me know!!!

It likely tries, but if home server is not available, nothing can talk to it.

If you are requesting something change or a feature to be added, it is not clear what that is.
I suggest adding more detail to your original request and better explain what you want changed.
As it is this does not appear to be a feature request.

And do remember that HA not reachable isn’t the same as HA is down.

There might be ways to check the websocket state from the frontend, but also keep in mind that the connection could be idle and only really disconnects upon use (when it realises it’s down) in case the connection has gone stale or failed.

If your instance is available externally through Nabu Casa, there’s a sensor to tell you whether it’s connected (server-side, of course; the app doesn’t know). That might help, depending your use case, but any ideas related to this will probably unreliable since there can be so many reasons for devices not being reachable.

The idea is to do what I have at work. At work, if we have a power failure the ajax alarm system sends a message with the reason (power failure) and phone ring with and alarm sound

I’m then failing to see how the original request relates to this.

Nonetheless, do you have UPS at home? You could monitor the power status with NUT.