Building Entrance protectors

Having an issue with House Cable.

I have a 50 pr installed with a BET at either end. From the BET’s I run D type 50 Pr to the telecom closets.

On pairs 1 and 2 , I am able to transmit a Mitel basic telephone.

A problem was discovered when the client bridsged a fax line ( POTS I am assuming ) from their main office to the plant ( so they could have 2 appearnaces ).

Using the same pairs i tested with the Mitel, the Fax line would fast busy itself out in about 10 seconds. If I placed a call, I could not release the circuit with the hookswitch and the only way was to remove the bridged jumper from the House cable field.

I used a Fluke DSp 4000 to line map and was able to reach one protector at 250 ft using the TDR feature, but could not get further, the cable run is about 1000 ft.

I used the resistance feature and on 4 pairs I had a reading of 400+ ohms, while some other pairs read “open”…..but always at the 250 ft distance.

If the client were to use all Mitel circuits , the cable plant seems to preform. This fax circuit is throwing me off.

Anyone have an opinion on what may be happening. Are the fuses blocking the circuit….is the circuit ” unbridgeable “….yes, it works as a standalone at the far end but not through the cable plant.

Any opinions are appreciated.