Build a self-contained Dial-a-Song using a Western Electric 2500DM telephone and a Feather RP2040 + mono amplifier. People can dial a number to hear a song or message played through the handset earpiece. The CircuitPython keypad library makes it simple to read the Touch Tone keypad matrix.
It's a fun conversation piece -- especially with its accurate dial tone, touch tones, and other teleco messages -- and perfect for escape rooms or other puzzle games.
I'm not going to tell you how to live your life. However, should you choose to put some They Might Be Giants songs on there, you'll be a hero.
You'll also need a 2.2µF electrolytic capacator for the RC noise filter circuit, although in a bind you can use this 10µF one.
Western Electric 2500DM Telephone
The classic! Grab a vintage Touch Tone phone out of your attic/basement or hit a flea market or yard sale. In a bind, you can find them on an online auction site for a reasonable amount.
Some older phones will come with a mechanical switching matrix, in which case you'll need to get a "newer" (early-1980s) electronic keypad, such as this one.
I haven't opened up the modern Cortelco ITT 2500, so I can't say if it can be wired the same way the older phones could.