Ever since I got cabinetised I've had problems with my phone but I can't decide which side of the demarc point it is. I'm hoping someone can help.

At the phone jack I can ring out but it wont ring in (some one rings me but the phone doesn't ring). Normally it goes to some sort of Telecom divert. Sometimes it wont ring and neither can I ring out. Some times if I ring out I have to unplug from the phone jack and replug it again to ring out again. Sometimes I'll ring out and hang up, go to ring another number and the line is still open to the previous call.
If I take the phone and plug it in the home hub test point then I can ring out AND it will ring in, but not always. I don't understand how on a two wire system it can ring out but wont ring in.
It doesn't seem to matter if the home-hub is plugged in or not.The only other info I can provide is that the voltage to the phone jack is about 50volts.

This is a description of my wiring.
I have the loose twisted pair coming into the roof. In there I have cat5 cable with one pair fed from a Telecom approved filter and one pair feeding the Orcon home hub thru a bt phone jack. Outside the home-hub jack the filtered cat5 twisted pair for the phone changes to a pair of the standard Telecom type 4strand cable with a couple of jell filled crimp connectors then on to the BT jack point by the phone.

I've tried to give as accurate picture as I can. Anyone any ideas !

Appreciate your help