Non-Bell phone loading line for other phones

[sajurcaju]

My Mother has a "French Phone" that she loves. It isn't an antique (plastic), I doubt it is French, it certainly isn't Bell System. When she is on her phone and my Dad is on his (rotary) phone, my Dad's voice is weak and distorted. When she hangs up, my Dad sounds great.

I think what I need is some sort of buffer between the "French Phone" and the rest of the phones to isolate it. Does such a thing exist? I haven't had any luck looking.

Thanks much,
Steve

[twocvbloke]

First thing to try is substituting the phones for different phones, to see if the problem remains or disappears when swapping out one or the other phone, so if you took out the "French phone" and replaced it with a generic off-the-shelf phone and the loss in quality remained, then it's the rotary, and vice versa if you remove the rotary and the problem persisted with the French Phone...