At the end of the 'jumper' the connecting wire between BTw telephony equipment and the bar pair.
On full LLU lines they also own/maintain the 'tie pairs' between the MDF and the LLU equipment.
Why do you ask ?
Curiosity in view of the potential split from the rest of BT.
On the Openreach website the faq says:
"Q6 What does 'improving service' look like?
Openreach strives not just to provide, maintain and repair the access and backhaul infrastructures, but to improve both service and reliability. We are also reinventing our infrastructure to support the continuing success of the UK telecommunications industry - ultimately enabling it to deliver more choice, better products and lower prices for its customers and to build profitable businesses."
which AIUI conflicts with what you said as it includes backhaul!