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•Alternatively, some users may wish to provide a uninterruptible power supply (UPS) for their modem and DVG (LAN) in these scenarios to keep the VoIP service active.
Given the relatively high cost of UPS per hour of backup, it is unreasonable to provide such backup for more than a few hours. Providing UPS capability for 24 hours or more becomes prohibitively expensive.
It is recommended to spend no more than $50-$120cdn on a small UPS (from APC or Belkin) for your ISP and VoIP service. This should give you "standby" power for a day or so and "talk" time of perhaps 8-10 hours or less; depending on the actual devices, configuration, and usage.
You can estimate your UPS requirements as follows:
• Get the INPUT current (AMPS), or INPUT Wattage, required for each device from the CSA or FCC stickers on the power supply for each device.
•Add the POWER for all devices to get the TOTAL WATTS that you need.
The TOTAL WATTS is what is required to keep your devices powered for each hour of operation. You can estimate how long a UPS will provide power by dividing the UPS "VA" value by your TOTAL WATTS. This results in the approximate number of hours the UPS will provide power to your devices. [ VA is like WATT (V=Volt * A=Amp)]
This is a simplified explanation and will be updated to include transformer heat loss. Note that this provides ratings for TALK time (when the devices are in use). If the TBB phone line is not being used, the calculated time will be higher.
You can also refer to »www.apc.com/tools/ups_selector/index.cfm
Using a Siemens 6300 DSL/wireless router modem at 20W, and the DLINK DVG 1120M which is rated at 22Watts: [ The TOTAL POWER = 20W + 22W = 42 Watts ]
Thus, a total power supply of about 42 Watts is required to keep just the modem and DVG ATA powered up. Using a UPS rated at 600VA and dividing this by 42 Watts provides a result of about 10+/- hours when takihng into account heat loss in the transformer and UPS.
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