Our home server runs Asterisk (*), the open source IP telephony environment (much more than just a PBX!).
We have 2 ISP and VOIP providers with a number of Lines. Our primary ISP is Andrews and Arnold as they have offered a comprehensive IPv6 service for many years, as well as IPv4.
Our last POTS line was discontinued in 2023. Internally we have been entirely IPT based for 20+ years.
There are a number of Video Phones around the house and an IP DECT base station for hands free phones.
What Asterisk does for us is handle voicemail with a multi function IVR menu system on the incoming lines and run an internal phone system around the house & garden.
Asterisk also prompts Misterhouse to ring some chimes when the doorbell is rung and to announce inbound CallerIDs or caller identities for known numbers over the Pi Consoles.
At our front door is an IPT Video Intercom for the doorbell. This initially rings all the internal phones and if not answered also calls a mobile number, before going to Voicemail.
The IVR menus allow an number of screening functions on incoming calls by incoming line, calling ID and time of day.
Misterhouse also uses an SMS gateway to keep us informed of events at home etc.