Router ADSL Phone Line Setting

[#1]

Not a problem but I noticed this setting on my Billion router.
Phone line pair Inner pair   Outer pair
I can select one or the other but I haven't done so. It just looks very puzzling considering there is only the one phone line socket on the back of the router

[#2]

it'll be referring to which pair of wires on the actual cabling/wire that is being used i would assume.

[#3]

But that would be a physical change inside the NTE.
Not something the router would know about or have any control over

[#4]

Seems its a reserved setting according to the manual.
Possible the designer thought he could tweak settings perhaps on a longer line depending on the pair used, then later realised it was a tweak too far, or needed the code for some other feature.

[#5]

Quote from: Strat

Phone line pair Inner pair   Outer pair

Quite likely referring to which pair of the RJ connector are used for the incoming telephone line.  Some countries use the inner, some the outer, and a 2-line setup (e.g. USA) can use both the inner and outer pairs for lines 1 + 2.