BT line testing

When I first moved into our new house I had a noisy line and terrible DSL connection. BT initially claimed I had no fault! Somewhere, I discovered that BT had a machine that would do a proper test even when the noise was absent. After a month or so of arguing a chap came along with the machine and discovered a corroded connection where the line joined the house.

My daughter is having exactly the same problem. My problem is that I cannot remember the name of the machine/test that I insisted BT should do!! I need to tell my daughter the name so she can insist on it.

Anyone know the name?

Thanks

Hawk?

TDR?

Hawk. Thanks