That's a common problem. Either it's a full short, or worse, an intermittent break or leakage which degrades voice quality and hurts dial up computer use.
I'm not an expert, but I'd say wiring technique is more critical today than in the past for plain voice service because data transmission is much more sensitive to things like crosstalk or interwire capacitance or plain old static. Perhaps another reader could offer suggestions.
My recommendation is to abandon all old phone wiring and rewire the house using modern standards that will give the best quality for high speed data transmission and multi-line phone service. Others can give tips on the best way to do this.
When we needed new wiring, we had the phone company do it for us. Not cheap but reliable. I presume a qualified electrician familiar with modern phone requirements could do so as well, possibly cheaper.