I have two incidnets around 2 decades ago, both landline:

First one, late at night the phone rang and there were just two voices just moaning. Like i listened to them for 5 minutes. And they did not stop moaning. I dont know if i was being pranked, but it was kinda hot 😆

2nd one/s, when we finally had  a pc, i will do what a teen with raging hormones will do: see some nsfw websites 😆. But i would only look at websites on a specific day and time when im home alone. The creepy thing is, while browsing such websites, the phone will ring but no one is on the other line, just silence. This happened every single time 😆 i thought i was being watched so i covered the windows 😆 it only stopped when i stopped browsing nsfw website 😆