[Arizhel]

>The phone will invariably ring and will either be a spam call or a call for one of them.

Simple solution: get rid of the phone. Why do you have it anyway? I haven't had a landline phone for probably 10 years now, and I was a little late to that party. This line of yours looks like something out of the 1990s: a phone call for someone else? How quaint! Do these people not have their own phones?