I own a house with a "C" shaped floorplan and walking around to ask someone a quick question can be a bit annoying. To solve this problem I considered just buying some DECT phones with a built in intercom (or some other off the shelf product) but what's the fun in that? As a weekend project I decided to build an intercom using Asterisk and some vintage phones.
Step one: Get on eBay and buy some vintage phones.
To start with I bought three model 500s, this "Empress" phone and some Grandstream HT801 ATAs to bring them all into the 21st century. The 500s are built like tanks while the Empress is as plasticky as it is ostentatious. I'm not sure what's up with the sticker or scare quotes around "ambulance service" but I left it in place when cleaning that phone.
One thing to note is that the 500 series phones all needed a jumper between G and L1 for the ringer to function:
Most of these were in decent enough shape and just needed minor repairs as well as a thorough cleaning in addition to the jumper. The Batphone had a sticky dial that needed a bit of disassembly and lube but was otherwise fine. The green phone was particularly disgusting on the inside and the handset cord was unsalvagable due to what I assume was decades of nicotine staining.
The rest of the setup was a vanilla install of Asterisk followed by assignment of extensions and other typical configuration items. Each phone uses a two digit extension like "1N" to make direct calls easier and faster. I also added a queue that rings all other phones if someone dials "0". The HT801 doesn't seem to have any trouble with the ringers on these ancient phones after enabling "High Ring Power" and was super easy to configure.
