Actually, this thread is not (officially) about that. There had been no mention of black cable until out of the blue (hey, hey, my, my) you said "And if you are using black telephone cable like BT do, where did you get it from " for no apparent reason...
Aye. The engineers have a special tool to do that - kind of a folding plastic thing with roller blades in set at just the right depth. I managed to source one, and it was very useful til it broke.
Maplin does black sheathed 3 pair telephone cable good for wiring telephone extensions round the outside - have done so for years.
You'll also be wanting black 5mm cable clips. You can get white ones anywhere but they look really naff holding up black cable outside; black is much better, but much harder to find.
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