It is proper netiquette to have a backup power supply for the connected computer in case of an emergency.
Power Supply Back Up Netiquette
It is good internet etiquette to have a backup power supply. So, VOIP adapter and connected computer in case of an emergency.
VOIP uses electricity. Telephone adapters must be plugged in or a computer must be on to use it through one. Electricity goes out for various reasons. Natural disasters frequently cause electricity outages and give rise to a need to use the telephone.
If there is no electricity for the VOIP it will not work. Back up power systems for computers and electronics are widely available. They use rechargeable batteries to supply power to computers in case of an outage.
Therefore, it is good netiquette to have a back up power supply for electronics. Given, VOIP is our primary number. Power outages frequently give rise for a need to use the telephone.