What is a POTS line?

POTS is what’s known as a retronym — a name that exists in order to distinguish an old thing from a similar, new thing. So, while these lines have existed for over a century, the term POTS is relatively new! It stands for Plain Old Telephone Service, and is also called PSTN, or Public Switched Telephone Network. It’s an old-school analog setup that uses copper wires to connect calls and keep things powered up. Before VoIP took over, POTS was the standard.

The invention of the electric telephone has some debate around it, with inventors like Antonio Meucci and Philipp Reis playing key roles. However, the main name associated with the technology is Alexander Graham Bell, who was granted a patent in 1876. Acoustic telephone-like devices existed before this (think, connecting two tin cans via a string and relying on sound transmission), but had limited range and functionality. Bell’s new telephone didn’t rely on transmitting sound waves — instead, it used electricity and wires.

When it was first designed, it relied on direct lines phone-to-phone, but what we think of as a POTS came into play shortly after with the invention of the telephone switchboard by Tivadar Puskás in his work for Thomas Edison. This allowed for calls to be direct via a central exchange — something that would eventually become the global network we use today.

What is a POTS line used for?

Essentially, POTS lines are the classic phone lines that handle your basic voice calls. They’re still used for traditional landline phones, but they also handle things like fax machines and alarm systems. Despite the rise of newer tech, POTS lines are reliable for essential communications and backup systems, especially in areas where modern alternatives aren’t available.

How do POTS lines work?

Even though POTS lines have had some updates over the years, the basics of how they work are pretty much the same. The biggest change is the loss of manual switchboard operators, as calls are now relayed automatically. Here’s a simple breakdown of how it all happens:

1. You dial a number and talk into the handset. The phone converts your voice into electrical signals.

2. These signals travel through the phone lines to a drop cable connected to a terminal.

3. The signals are sent via an aerial cable to the main phone company office.

4. Automated switches at the office decode the signals and figure out where they need to go.

5. The signals are then sent either to a tandem office or directly to a central office closer to the call’s destination.

6. More switches in the main office route the call to the right terminal.

7. Finally, the call reaches local lines and connects to the network of the person you're calling.

8. The handset then turns those electrical signals back into sound waves, so you can hear the other person’s voice!

POTS technology

Wondering about the technology behind this system? Let’s look at three crucial bits of technology in the history of the Plain Old Telephone System.

Circuit switching

Communication nodes would let two points connect to the network, and calls were routed through different switches depending on how far the call had to go. Those copper lines were prone to interference, so they were used for just one call at a time unless they were switched. This method is called circuit switching.

Historically this was a hands-on job done by people sitting at big switchboards in central offices. Their role was to plug copper lines into a patch panel to connect calls between two people. If the call needed more than one switch, extra operators would step in to hook up all the lines to the same trunk (that’s the main wire). Since everything was done manually and required a lot of people for long-distance calls, the costs could really add up. Basically, the farther the call had to go, the more copper wire was needed, and that meant a bigger bill. Thankfully, circuit switching got a makeover with the invention of the transistor.

Transistors

This particular bit of tech played a big role in moving toward digital networks. Today’s phone lines use digital signals called "packets," which let voice and data travel separately through switches. Copper lines still carry voice back and forth, but digital signals need extra hardware to handle the 0s and 1s. There’s no need for a whole new system, just some extra gear to get those signals through.

Modems

Enter the modem! It’s the piece of tech that helps update old POTS systems with digital technology. There are two main types: DSL and ISDN.

• DSL (Digital Subscriber Line) uses existing copper wires to send data. It connects a computer to the internet through your phone network, which is great for small businesses needing multiple users online.

• ISDN (Integrated Services Digital Network) also uses traditional phone lines, but does so with better speed and quality. It can handle both voice and data, plus it offers features like call holding, on-hold music, and call routing.

Here’s a more detailed overview:

• Technology: PSTN relies on physical infrastructure like copper lines and telephone poles, which can get damaged by storms or age over time. This setup needs constant maintenance, adding to the costs. Plus, adding new lines or expanding service means a lot of digging and construction — definitely not ideal for quick changes or rapid business growth. That’s why VoIP is great — it's modern, versatile, and leverages the latest tech.

• Cost: Running a PSTN system isn’t cheap. You’re looking at expensive maintenance bills and higher costs for long-distance and international calls. For businesses that frequently make international calls, these costs can add up quickly, making PSTN a pricey option in today’s global market. VoIP pricing is typically lower, especially for international calls, and is more budget-friendly overall. Plus, there’s no physical maintenance to pay for.

• Flexibility: POTS can be tough and limiting. VoIP, on the other hand, is super flexible. You can easily add features or scale up, making it really easy to adapt as your business grows.

• Features: With POTS, you’re stuck with the basics like caller ID and call forwarding. VoIP brings a ton of advanced features to the table, like video conferencing, virtual numbers, call forwarding, conference calling, and voicemail-to-email. Plus, VoIP also seamlessly integrates to other business tech like your CRM system.

• Reliability: One of the only places where a POTS line bests VoIP is with reliability. That’s because POTS doesn’t have to rely on the internet, whereas VoIP does. So if your internet’s slow or you’re dealing with high traffic, you might experience lag or dropped calls. Plus, local power outages can knock out your VoIP system unless you’ve got backup batteries in place.

• Installation: Setting up a POTS line involves a lot of physical wiring (we’re talking long stretches of copper cables running through walls and up telephone poles.) You might need to dig trenches or make some serious adjustments to your office setup. It often takes time and effort to get everything wired and working correctly. On the flip side, VoIP is much easier to set up. It’s more like plugging in a new gadget — just connect your VoIP system to your existing internet connection, and you’re good to go.

• Voice quality: POTS lines generally offer pretty decent voice quality, and you can count on a reliable connection most of the time. However, they’re not immune to interference from things like weather conditions or physical damage to the lines. Sometimes, you might hear static or experience issues that affect the clarity of your call. VoIP often delivers excellent voice clarity, provided you have enough internet bandwidth. When you have a fast and stable internet connection, VoIP can offer clear, crisp calls with minimal issues.

• International calls: Making those long-distance calls with POTS can cost a lot. This can be a significant drawback if your business relies on international communication. VoIP shines when it comes to international calling. It usually offers much cheaper rates for calls abroad. This is a huge benefit if you’re doing business with clients or partners overseas, as well as if you operate a global remote team.

Considering using a POTS line in your organization? VoIP may be what you need instead

So, there you have it — the details on what POTS is, the benefits and drawbacks, and some modern alternatives. With how many places are retiring their POTS lines and the sheer lack of features available, it’s probably time to upgrade your communications.

A solution like Vonage Business Communications will let you make calls just like the PSTN does, but it will also give you access to so much more. With video conferencing, a virtual receptionist, and integrations with leading business apps like Salesforce, Zendesk, and Slack, it’s a great way to streamline and modernize communications. Plus, we offer 99.999% uptime*, so you don’t need to worry about losing the reliability POTS brings.

^{*The 99.999% claim is based on Vonage's average up-time and/or availability.}