Apologies in advance if my terminology is wrong, or if this has been answered and my searches have missed it.

My in-laws have moved into a new(ish) house that has data cabling throughout, terminating in a data cupboard in the garage which also houses the ONT. Rightly or wrongly they have a landline phone which they want to keep. It is currently connected to the RJ11 (?) POTS port on the ONT and working fine. However, I would like to use the patch panel to connect one of the ethernet ports in the living room to the POTS port on the ONT so they can have their phone there.

Google suggests it's possible with the use of an adaptor, but I am not sure exactly what I need to get. I have done a few searches in PB Tech, Jaycar etc but can't find anything obvious (to me).

Can anyone offer some guidance?

Cheers, Nick.