Old Payphones Get Modern VoIP Upgrade

Remember pay phones? Those relics of telecom’s distant past were once everywhere—on many busy street corners, in bars and restaurants, even built into airliners’ seatbacks. Now, an engineer in Vermont is aiming to give the old-fashioned device some present-day relevance.

Patrick Schlott, 32, is an electrical engineer by training who works at the South Burlington, Vt.-based eVTOL maker Beta Technologies. Inspired in part by the free-phone projects Futel and PhilTel, he’s restored and installed free-to-use pay phones at over half a dozen locations across Vermont. With Schlott’s phones, users can make coinless calls anywhere in the United States or Canada—with each phone routing its calls through local internet connections via a simple voice over IP (VoIP) gateway.

Schlott recently spoke with IEEE Spectrum about the rugged charm of old tech, public phones in a private world, and the joys of reverse engineering.

IEEE Spectrum: How’d you get the idea to convert old phones into free-to-use public pay phones?

Patrick Schlott: In early 2023, I was visiting my parents’ house, and I found an old piece of phone equipment in the garage. It was basically a hook switch and a handset. I’m a big enthusiast of old technology, so I thought maybe I can get the rest of the parts and make it into a working telephone. Around the same time, a friend who works in IT said there are these gateway devices that convert a digital VoIP telephone line to analog. At the time, I was living in Tunbridge, Vt., with my now wife. I thought it would be great to have a phone for people to use out there when there’s no cell service.

Spectrum: How did you decide where to install your first phone?

Schlott: My wife and I frequented the North Tunbridge General Store, and in early 2024, I approached Mike Gross, the store owner, about this project. I explained if he just gives me internet, I’ll provide the phone, pay for the service, and make sure the network is secure and that phone traffic is encrypted. And he was like, “I don’t know that I would want people messing around with the phone on my porch after hours.” But his wife Lois, who’s a co-owner of the store, was like, “Oh, that would be great because people’s cars break down sometimes, and we get people asking to use the phone occasionally.” Also, around this time, there was a woman at a campground who had a dispute with her partner and ended up walking 10 or 15 miles to the store. She really could have used a phone. A couple of weeks later, I went to the store, and Mike was like, “So I’ve been thinking about your phone project—let’s do it.” In March 2024, that first phone went in.

What Is Needed to Convert Old Phones?

Spectrum: What went into converting old phone parts into a working phone?

Schlott: Phones used to operate on two types of telephone lines: ground start and loop start. Ground start phones expect a ground start circuit; you can’t just plug a regular landline into these phones in 2025 and expect them to work. Not a lot of people have landlines these days, but if you do, it’s a loop start line. Basically it’s an electrical circuit—a loop. The phones I work with are designed for a loop start telephone line. With the loop start, the technology that makes the phone work is called an ATA or analog telephone adapter. They’re also referred to as SIP [session initiation protocol] gateways or media gateways. These gateways connect to a VoIP telephone system. I pay for VoIP phone service, and I use the ATAs to connect right to the provider. It’s like you’re getting a landline over the Internet and then connecting it to a pay phone that operates like an analog telephone.

Spectrum: If any phone will work with the gateways, why bother using pay phones?

Schlott: The biggest reason is, if you’re old enough to know what a pay phone is, and you see one of these old Western Electric and GTE pay phones, you instantly know that’s public infrastructure for you. You don’t have to ask for permission. You can just go up and use it. If it’s just a courtesy phone, it’s not always 100% clear what that’s for or if it’s okay to use. Also, pay phones are cool. There’s a lot of history behind them. And pay phones are rugged. They were built to withstand abuse and be outdoors for decades.

Spectrum: Have you added any functionality to the phones?

Schlott: There are certain numbers that get dialed when you dial certain codes. So, if you dial 0, I have a softphone app on my personal cell phone that rings. I’m the only operator for right now. Also, if you dial 211, the phone calls Vermont United Way. Same for other codes, like 411 for directory assistance and 988 for the suicide hotline. Operators do not handle emergency calls. And I’ve made sure that the E911 [enhanced 911] address for each install location is registered with my provider, so if somebody needs to dial 911, their address is passed along to the answering point.

Who Uses Pay Phones Today?

Spectrum: How many phones have you installed so far, and where are they?

Schlott: There are seven phones installed as of now in libraries, schools, and a town hall. I have three on the books immediately, and I’ve got more behind them at community centers, more schools, more libraries. After the first phone in Tunbridge, everyone else has requested the phones.

Spectrum: What’s driving the demand?

Schlott: The two big factors are kids at school that need to make phone calls and the lack of cell service. The state of Vermont passed a bill to ban the use of smartphones in schools starting in September of 2026. School administrators and parents in the community see a need, and my project fills that gap.

Spectrum: How do you cover the installation and operation costs?

Schlott: I fund it through donations and my own money. The used pay phone market is kind of ridiculous, cost-wise. The prices are all over the place. If you go on eBay, you will very easily see pay phones for $400 to $700. But you go on Craigslist or Facebook Marketplace, maybe you’ll see somebody who’s not really a pay phone enthusiast and just wants to get rid of it for $50 or $100. It depends on the conditions. Paying for the phone service only amounts to a few dollars per month per line.

Spectrum: Your phones are free to use, but do they accept coins?

Schlott: In a lot of the phones, I’ve left the coin mechanisms intact. I want them to be exploratory and hacker friendly. People who are familiar with the phrases red boxing or phone phreaking will understand why that’s important. I have future plans that involve coin functionality purely for fun, not for profit.

Spectrum: Were there any surprises with the phone restorations?

Schlott: A few phones were damaged or weren’t wired the way I expected. On at least one phone, I had to do a good amount of reverse engineering, like tracing circuit diagrams and referencing old documentation from various phone manufacturers. Sometimes the phones are locked. I’ve got to find the keys or drill or pick the lock and then figure out what the electronics are like inside. I’ve learned so much about so many different types of phones.