I got a second line in years ago and is it a benefit? .... hell yes..... when the service goes down even for a few hours it can be a right PIA.... Always happens at the weekend or so it seems
With the amount of equipment using the internet now it makes sense [to me anyway] for a second line, You can get 12 month free deals on some providers so cost could be next to nothing. Swap to a different provider or platform at the end of a contract to keep the cost down [if cost is important]
If you get another line keep your existing line with a decent provider for phone and broadband, use the other line to swap deals and not actually worry about the phone number. ADSL or fibre deals on LLU or BT network.
The reason I say keep one line with a static provider is during a swap over from a provider a good few years ago I lost or sorry they lost a phone number I had for a long time..
A mix up their end cancelled the number and it was gone.
For back up keep the lines on a different supplier say BT for one line using their backhaul [adsl] and Sky for another line using their LLU, that way if there is a exchange problem then both lines may not be affected
If someone drives a bus over your cabinet then tough luck
or would that matter if it was fibre & adsl hmmmmm
Right now I cant talk as both my lines are in the same place.!!!
ZeN Line 1 BQM
ZeN Line 2 BQM
BT Backhaul sucks