my wife had a requirement: be able to have an intercom for the house and shed. We used to have a baby monitor, but that was one way, for one room. Now we need many more rooms to talk to each other.
I looked at some intercoms on amazon/ebay, they are all RF and a bit shit. I saw some wifi ones, but nothing cheap enough to take a punt on. I did think about trying to make something with an ESP32, but that would be too hard for me in the time.
So I bought 6 cisco 7962 sip phones for £35 in total, and installed freepbx.
It took a bit of effort to bring the tftp server online, and make sure all the dhcp info was being passed on correctly. Once that was complete, freepbx makes most things pretty simple.
Now, I have ethernet is most rooms, and a switch that can do PoE, so this solution is for a niche of a niche
I actually run 7962g + FreePBX too, using sccp_manager and phone-integrated SSL-VPN. It took more hair pulling and shady patching than the SIP route, but now I can make intercom calls over the Internet! That way I don't need a direct L1/L2 link between "offices". Solves NAT problems too, because it's all in-band signaling and media transport over single TCP connection.
I remember playing with an old device as a child at my grandparents' place, it was similar to a walkie-talkie but transmitting using the mains power instead of RF. It was supposed to plugged to a socket and hanged on the wall. It was made exactly for the use case you describe, as an intercom between rooms. It even had a button to ring a bell in another room.
I hope you ran optical between the house and the shed. The difference in ground potential among buildings can cause a lot of trouble for copper/electrical connections.
I looked at some intercoms on amazon/ebay, they are all RF and a bit shit. I saw some wifi ones, but nothing cheap enough to take a punt on. I did think about trying to make something with an ESP32, but that would be too hard for me in the time.
So I bought 6 cisco 7962 sip phones for £35 in total, and installed freepbx.
It took a bit of effort to bring the tftp server online, and make sure all the dhcp info was being passed on correctly. Once that was complete, freepbx makes most things pretty simple.
Now, I have ethernet is most rooms, and a switch that can do PoE, so this solution is for a niche of a niche