We have FiOS triple play with TV, internet, and FiOS digital voice. The phone line from the ONT goes to a terminal block, and then extension lines go from there to various rooms. Connected to the phone line is a caller id box with an ac adapter, a cordless phone base unit with an ac adapter, a phone with its own battery power, a digital answering machine with its own ac power adapter, and one phone-line powered phone. The latter two are connected to a dual jack wired to a single extension run, and these are what I'm having trouble with.
We prefer having an answering machine in the house instead of using the FiOS voicemail so that we can screen those calls that have unfamiliar numbers on the caller id, or if it's just someone we don't want to talk to 🙂 The problem arises when we hear someone we want or need to talk to and we pick up the phone to talk to them, it doesn't work like it used to, the answering machine seems to hog the line and they can't hear us talking. It didn't used to work that way, the answering machine speaker and the phone would both work simultaneously for a few seconds, causing feedback if standing too close, and then the answering machine would disconnect itself.
We used to have a single jack with a "y" adapter for the phone and answering machine, but it didn't click and lock in and the cats were always knocking it loose so we put in a dual jack there, but that didn't fix the problem. There have been no other changes to the wiring or equipment for years.
Is it possible that the ONT is no longer putting enough voltage or current on the line to have the answering machine and phone off hook at the same time? If I answer the self powered phone in one room at the same time the line powered phone is picked up in the other room they both work at the same time.