How to Make a Direct Connection Between Two Landline Telephones

Alastair Aitchison's Playful Technology is a fantastic YouTube channel that focuses primarily on technical builds for escape rooms — projects that make puzzles more fun and interactive. Aitchison's most recent video is a great example, as it explains how to make a direct connection between two landline telephones.

This setup makes it possible for one landline telephone to call another using a phone number, just like you would have done before cell phones came along. It provides dial tones and ringers, so everything works as users expect. The same setup can also be used for an intercom-style arrangement, if preferred. All of that works with local hardware and doesn’t require any kind of complex switchboard or service.

I’m sure you can imagine some great applications for this in an escape room. Maybe the players are divided into two teams that go in separate rooms and they have to call each other with clues to solve their respective puzzles. The possibilities are endless!

Aitchison walks viewers through how to achieve that using only a single device: a Grandstream HT802 ATA. You can easily find one of those brand-new online for about $40-50. Other than that, you just need two landline telephones and some cords. The entire setup should cost well under $100.

Configuring the Grandstream HT802 does require network connectivity over Ethernet. That gives you access to a web interface to enter the settings, like the phone numbers you want to use. After configuration, you can disconnect the Ethernet connectivity, as network access won’t be necessary for the phone call functionality.

That’s it! Now the phones can call each other and you can use them however you like, whether that is for an escape room or some other application.