It was a "BT Line" before Openreach was formed. Some people, even occasional newbies to these forums still refer to having GPO lines.
Things don't change that easily, particularly in the case of Openreach which still belongs hook, line and sinker to BT.
In any case, prior to Openreach existing, what "BT Line" meant was a BT Wholesale line. However, nobody but pedants like me ever referred to it like that. Most of the time, that is still the appropriate description when explaining the foibles of broadband ordering from different retailers.
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