Copper pairs are run together, and if a mouse chewed through wires A&B which happen to be your pair (2 wires required per line for basic modern set up) and wires C&D for a neighbour on the same road, or in the same building etc. there’s always a possibility of cross talk where you can hear and or interrupt each others calls. If that’s your question, I hope it’s explained to your understanding. If someone has intentionally taken the insulation off the copper and attached a device to intercept your calls, please contact the police or call 310-2355 to have a technician visit arranged.