When you mention a 'battery backup device for the router and phone' do you mean a way to keep power supplied to those in the event of a power cut or do you mean a device to allow you to call out still if the power to those devices is off?
Keeping power supplied to the hub and phone might only be useful if the power outage is very localised indeed because, in a wider power cut, other parts of the VM network may also lose power even if the equipment in the home is still running.
VM do offer an emergency backup line to vulnerable customers (see p35 to 37 of the manual link above) but it will only dial 999. It requires a simple corded handset and connects via the mobile network to place 999 calls.
What you have to bear in mind is a lot of VMs local network is carried on copper coaxial cables. The fibre part of the network could be 500 to 1000 metres back in another housing estate. If the fibre/coax node or any powered amplifiers between you & the node lose power, you lose all your services.
As network segments become smaller & fibre comes to some of the coax splitter cabinets it will be less likely you will lose service if an adjacent area loses power. But having a UPS on the Hub is unlikely to be a worthy investment as more often than not the new node will be on the same electrical supply section as your house.
VM BB TV Landline. Vonage 2nd line. Freeview/Freesat HD, ASDA/Tesco PAYG Mobile. Customer since 1993
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