We're currently looking into upgrading our UPS and possibly having a small petrol generator on site in the eventuality that the UPS battery is used long enough to drain it completely.
Realistically, we can only afford a UPS that would give us around 45 minutes. It's not unheard of for our building to have outages of 4-6 hours. It is very rare though.
What products are available that are capable of sending notification (SMS, automated call, etc.) when a UPS switches to battery power? Some UPS's we've looked at have serial connections. How do you deal with this kind of thing?
The plan is that when the power goes down, the battery takes over and alerts the team. One of us (whomever is on call) drives the the building and starts the generator. Unless of course a notification comes through that the power is back on.
We do currently use Pingdom to monitor uptime of our services. It's just a ping test though so we can't rely on a lost host to explain why it's lost. For example; if the network connection went down and so did the backup link, we would get a notification. That doesn't necessarily mean the generator needs to be started.