But you still need to keep One or Two Analog POTS (Plain Old Telephone Service) lines that come straight from Ye Olde Phone Company on copper cables. Because it's no-nonsense 99.9999% reliable - that's downtime measured in seconds per year.
Try calling 911 on the VOIP with the power out, and it probably is not going through. The POTS line, you pick it up and you'll get that same boring old Dial Tone damn near every time.
You want to do the same thing that the Phone Company does - except they have an emergency line coming in from ANOTHER neighboring central office, so if their switch ever did go down that hard...
Hang a red single-line telephone on the wall, or a desk set on a little shelf in the hall with the loudest "wake the dead" gong ringer you can find. And the employees and spouses know the Emergency Number
- and if you call it, it better be a real emergency.
That's the phone line (that still works) you call out on to ream the Cable Company a new one when the main service goes down again. As you'll find out, there's no FCC Mandate for reliable service on Cable VOIP or other transmission methods than POTS.
If the Cable Co. loses power to one amplifier anywhere on the path back to the head-end (or all of them when the entire town goes down) the backup battery there (totally optional, BTW) might last an hour and then they are going down hard till someone finds and fixes the problem.
You might want a separate second analog line for the Burglar and Fire Alarm systems to call out on, and that can double as your Fax line.
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