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POTS Lines: How Plain Old Telephone Service Works?

Dive into the world of Plain Old Telephone Service (POTS), the original telecommunication system that has connected voices across distances for over a century. Despite the rise of advanced digital solutions, analog POTS lines have a storied past and still play a role today. This article explores the fundamental principles, enduring presence, and how traditional telephony contrasts with modern telephony solutions.

What is a POTS line?

POTS, acronym for “Plain Old Telephone Service, is the traditional analog voice transmission phone system that has been in use since the late 19th century. This system operates on copper phone lines to deliver analog voice signals, not to be confused with “Post Office Telephone Service,” as they would read it back in the day.
Cable lines are characterized by their simplicity and direct connections. They use a pair of copper wires to create a single phone circuit capable of handling one phone call at a time. These lines are also known for their reliability, particularly in powering through electrical outages, due to their independent power source. However, with advancements in technology, telecom lines are gradually being replaced by more modern solutions.

How does a POTS line work?

In the past

The functioning of cable lines in the past was a miracle of analog engineering, characterized by a step-by-step process:

  1. Initiating a call: When a user dialed a number on a rotary phone, each digit created a series of electrical pulses. In touch-tone phones, each button pressed generated a unique tone.
  2. Signal transmission: These pulses, or tones, traveled as an electrical signal through the copper wire connected to the phone.
  3. Connecting through the exchange: The signal reached a local telephone exchange where, in the earliest systems, human operators manually connected calls using switchboards. This created a physical circuit between the caller and the receiver.
  4. Call completion: The circuit remained open for the duration of the call, allowing voice signals to be continuously transmitted as electrical signals over the wires.
  5. Disconnecting: Once the call ended, hanging up the phone would break the circuit, signaling the exchange to disconnect the call.


The modern POTS line used for communication still follows a similar basic process, but with some key updates:

  1. Dialing: Dialing sends an electronic signal (still via copper lines), which is more efficient compared to the older rotary or tone systems.
  2. Digital conversion: At the local exchange, the analog signal from the copper line is often converted into a digital format. This aids in more efficient routing and reduces noise and signal degradation.
  3. Routing: Advanced digital switching systems then route the call through the network, selecting the most efficient path to the destination.
  4. Reconversion to analog: Once the signal reaches the local exchange near the destination, it is converted back to an analog signal.
  5. Completion and disconnecting: The receiving phone interprets the analog signal, allowing the conversation to occur. When the call ends, the disconnection process is similar, where hanging up the phone breaks the circuit, signaling the network to terminate the call.

History of POTS lines

The history of what POTS lines are is intertwined with the evolution of communication:

  • Early beginnings: The foundational concept of telephone lines emerged in the 19th century. Alexander Graham Bell is credited with inventing the first practical telephone in 1876, marking the advent of communication technology.
  • Widespread adoption: By the early 20th century, telephone lines became commonplace in urban areas, with wires expanding rapidly to connect homes and businesses across cities and eventually rural areas.
  • Direct dialing innovation: The introduction of direct dialing in the 1950s revolutionized telephone services, eliminating the need for operator-assisted calls and fostering greater independence in communication. Post Office Telephone Service providers and other companies were actively using it.
  • Transition to digital: The late 20th century saw the gradual shift from analog to digital transmission in telephone networks, enhancing call quality and efficiency.
  • The Modern Era: Despite the advent of cellular and VoIP technologies, traditional lines remain in use, especially in areas with limited access to advanced communication infrastructures.

Exploring the POTS technology

Traditional technology encompasses various components that work together to enable voice communication over distance. Let’s get into the critical elements that define this technology.

Circuit switching

Circuit switching is the foundational principle behind analog telephone system technology. It involves establishing a dedicated communication path between two points for the duration of a call. This method ensures a constant and uninterrupted voice channel, delivering clear and stable communication. The system relies on a network of switches that physically connect calls through a series of interconnected nodes, making it possible to maintain a continuous signal flow between callers.


Transistors, the tiny but mighty components in electronic devices, play a crucial role in phone systems. They serve as switches or signal amplifiers in phone exchanges. Transistors replaced earlier electromechanical systems, providing greater reliability, reduced size, and enhanced efficiency in telephone service networks. Their ability to control electronic signals underpins much of the functionality in the switching equipment used in analog phones.


In the context of wire technology, modems (modulator-demodulators) are essential for converting digital data from computers into analog signals suitable for transmission over telephone lines. Initially used for dial-up internet connections, modems enable the encoding and decoding of data, allowing computers to communicate over the POTS network. This capability was crucial in the early days of the internet, bridging the gap between digital computing and analog communication.

Digital Subscriber Line (DSL)

Digital Subscriber Line (DSL) technology revolutionized analog phones by allowing high-speed internet access over traditional telephone service lines. DSL modems utilize higher frequency bands for data transmission without interfering with the voice signal. This innovation made it possible to use the internet and make phone calls simultaneously, greatly enhancing the functionality of existing phone infrastructure.

Integrated Services Digital Network (ISDN)

The Integrated Services Digital Network (ISDN) represents an evolution of communication, enabling the transmission of voice, video, data, and other network services over the traditional circuits of the public switched phone service network. ISDN integrates both voice and data on the same lines by digitally transmitting signals, offering better quality and higher speeds compared to traditional analog systems. This technology marked a significant step towards modern communication, laying the groundwork for future digital networks.

Evaluating POTS for business: Key considerations

Certain limitations have emerged in the context of modern business needs. Let’s explore some of these shortcomings.

Limited scalability

Traditional lines inherently lack scalability, especially when compared to digital alternatives. Expanding a business with a regular phone line means physically installing additional lines for each new connection, which can be both costly and time-consuming.

Lower data capabilities

In an era where high-speed data transfer is crucial, analog lines fall short. They are designed primarily for voice communication and offer limited bandwidth, making them unsuitable for businesses requiring substantial data transmission or high-speed internet access.

Maintenance and infrastructure

The aging infrastructure of POTS networking can lead to higher maintenance costs. As these systems age, finding replacement parts and skilled technicians for repairs becomes increasingly challenging and expensive. This issue is compounded by the communications industry’s shift towards more advanced technologies, leading to a gradual phasing out of old phone systems and services.

Absence of advanced features

POTS lines lack the advanced features that modern VoIP or digital communication systems offer, such as voicemail to email, call forwarding to mobile devices, and video conferencing capabilities.

Is there any alternative to POTS lines?

Yes, VoIP is a great alternative to old-school POTS lines. It’s a way to make phone calls over the internet instead of using traditional phone lines. Simple and cost-effective, VoIP works by sending your voice over as data, just like sending an email.
With VoIP, all you need is a good network connection, and you’re set to make calls. You can use a special VoIP phone, your computer, or even your mobile. It often comes with extra features, such as video calls or messaging, all without the complications of a traditional phone setup.

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Feature VoIP (Voice over Internet Protocol) Plain Old Telephone Service
Toll-free and Local Numbers Offers both with easy management online. Provides these, but with less flexibility.
SMS/MMS Allows for integrated text and media messaging services. Not available; only voice communication.
Number Porting Seamless transition of existing numbers. Possible but may be more complex.
Music on Hold Customizable options available. Standard music or tones, less customizable.
STIR/SHAKEN Advanced caller verification protocols. Does not support these protocols.
Emergency Calling May have limitations with location tracing, depends on the provider Consistent location tracing for emergencies.
Webphone/Softphones Software-based phones for flexibility. Requires physical desk phones.
Mobile App Full business phone functionality on the go. No mobile app support, just phone lines.
Voicemail Options Voicemail to text/email, custom greetings. Basic voicemail functionality.
Call Logs and Notes Detailed records and note-taking capabilities. Limited call logging, no integrated note-taking.
Call Management Features Advanced features like call routing, queues, and screening. Basic call management without advanced routing.
IVR/ACD Multi-level systems for customer self-service and call distribution. Basic IVR, no ACD capabilities.
Call Analytics & Monitoring Comprehensive analytics and live monitoring features. Minimal analytics, no live monitoring.
Integration & Automation Extensive options including CRM and automation platforms. No direct integration capabilities.
User & Team Management Advanced user extensions, roles, permissions, and workspaces. Basic user management, limited to extensions.

Analysis and conclusion

VoIP technologies work by offering comprehensive communication solutions that are scalable, cost-effective, and integrate seamlessly with other business tools and platforms.
POTS lines serve as a reliable, if not basic, communication method with limited features but are valued for their simplicity and dependability, especially in terms of emergency services and uninterrupted service during power outages.
For businesses prioritizing advanced communication features, data integration, and flexible user management, VoIP would be the preferred choice. Traditional phones may still appeal to those with minimal communication needs or in areas with unreliable connectivity, ensuring essential communication lines remain open. The decision ultimately is based on a business’s specific needs, resources, and goals in their communication strategy.

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How much does a POTS system cost?

The cost varies for consumers and businesses, based on numerous factors including the amount of lines, features, and usage.

For consumers

Individual consumers typically pay between $20 and $50 per month for a basic analog line. This fee usually includes unlimited local calls, but long-distance calls often incur additional charges that can range from cents to several dollars per minute, depending on the carrier and plan. Additional features like caller ID, voicemail, or call waiting may also add to the monthly bill.

For business

For businesses, the expenses escalate due to the necessity for multiple lines and more sophisticated services. A basic business POTS landline can cost anywhere from $40 to $100 per line each month. When factoring in essential services like multiple extensions, international calling, and directory listings, the total cost can swiftly increase.

In comparison

VoIP solutions typically offer a more cost-efficient and feature-rich alternative. VoIP services can start as low as $20 per line, with bulk or package deals leading to greater savings. Moreover, VoIP services often include a suite of features at no extra cost, which POTS phones usually charge for, such as voicemail-to-email, call forwarding, and advanced call handling features.
The potential savings for both consumers and businesses when switching to VoIP can be significant. Consumers can save up to 40–50% on their phone bills, especially if they make international calls. Businesses, depending on their size and call volume, can expect savings in the range of 30–50% annually. Additionally, the reduced need for hardware maintenance and the ease of scaling as the business grows contribute to long-term cost efficiency, making VoIP an attractive alternative to traditional POTS phone lines for cost-conscious users.

Who uses Plain Old Telephone Service?

Historically, POTS service was the standard for:

  • Residential users: For in-home personal communication.
  • Small businesses: As an affordable and simple solution for business communications.
  • Rural areas: Where advanced infrastructure was not available.
  • Government institutions: Joined for the reliability of POTS phone system for critical communication.
    In the modern context, the use of POTS system has dwindled but remains in place for:
  • Emergency systems: Like elevators and alarm systems, a dedicated line is required.
  • Rural communities: Where newer technologies have yet to be fully implemented.
  • Older demographics: Individuals who are comfortable with traditional technology and resist change.
  • Specific business needs: Where reliability and simplicity outweigh the benefits of more advanced systems.

What should you consider when replacing POTS lines?

When considering the switch from POTS telephone system to more modern solutions, keep the following points in mind:

  • Compatibility: Ensure your current equipment, like fax machines, alarm systems, and modems, will work with the new technology.
  • Cost: Evaluate the upfront costs of new equipment and potential savings on monthly bills.
  • Reliability: Assess the dependability of the new service, especially in power outages or emergencies.
  • Features: Consider the additional functionalities you’ll gain, such as voicemail-to-email, and if they align with your needs.
  • Transition: Plan for a smooth transition without disrupting business operations, which may include a phased approach or temporary call-forwarding arrangements.

Upgrade from your old phone lines to a modern communication system

Transitioning from old phone lines to modern communication solutions offers unmatched flexibility and scalability for businesses looking to grow and adapt in the digital age. Not only does it simplify infrastructure, but it also provides a suite of advanced features to enhance customer interaction and support remote work dynamics.
Consider MightyCall’s services for a powerful upgrade. Our VoIP system is designed to integrate effortlessly with your business, providing reliability, cost-efficiency, and a multitude of features made for your specific operational needs. Embrace the future of communication with confidence, and let us improve your company’s connectivity.

Kat Barannikova
Kat Barannikova is a copywriter and an obsessive tea drinker at MightyCall.
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