Remember landlines? Plain Old Telephone Service — POTS for short — is the analog phone technology that has connected offices, homes, fax machines, alarm panels, elevators, and payment terminals for well over a century. It still works. The problem is that fewer and fewer providers want to keep maintaining the copper network underneath it, and businesses that haven’t planned a replacement are starting to feel the squeeze.
This guide covers how POTS actually works, why the industry is retiring it, and how businesses can choose the right replacement for each piece of equipment still depending on a copper line.
What Is a POTS Line?
POTS is traditional analog voice service delivered over twisted-pair copper wiring through the Public Switched Telephone Network (PSTN) — the same basic telephone infrastructure that has supported voice calls since the earliest days of the telephone. A few characteristics define it:
- Copper wire foundation: POTS runs over a physical copper network, much of which has been in the ground or on poles for decades.
- Centrally powered: Power comes from the phone company’s central office rather than a wall outlet, which is why a traditional landline can sometimes keep working during a local power outage.
- Dedicated connection: Circuit switching reserves a physical connection between two callers for the entire length of the call.
- Single-line operation: A standard POTS line typically supports one call at a time.
POTS vs. PSTN vs. VoIP: Sorting Out the Terms
| Term | Meaning |
|---|---|
| POTS | Traditional analog telephone service delivered over copper lines |
| PSTN | The broader public telephone network, including both analog and digital components |
| VoIP | Voice communication that converts calls into digital data and sends them over an internet connection |
How a POTS Line Actually Works
A POTS connection runs from the phone company’s central office to a building’s network interface box, and internal wiring carries it from there to individual jacks and devices. When a call is placed, the network reserves a dedicated circuit between the two phones for the duration of the call — a handset converts voice into analog electrical signals, those signals travel over copper to the recipient’s phone, and the receiving handset converts them back into sound. When either party hangs up, the circuit releases and returns to standby.
Where POTS Lines Are Still Doing Real Work
Plenty of equipment still depends on a POTS line specifically because of how simple and power-independent it is:
- Fax machines that send and receive scanned documents over the phone network.
- Payment terminals, particularly in locations with limited or unreliable internet access.
- Alarm and security systems that rely on the line staying active during a power outage.
- Elevator phones, which provide a direct wired connection to emergency responders.
- DSL internet service, which is delivered over a POTS line using a modem and filters to separate voice and data.
Every one of these use cases needs its own migration plan, since the right replacement depends entirely on the equipment involved: fax machines may move to online faxing or an analog telephone adapter (ATA), alarm systems often move to a cellular communicator, elevators typically need a cellular or IP-based emergency dialer approved by code, and payment terminals usually just need a reliable internet or cellular connection.
The Copper Sunset: Why POTS Is Being Retired
For decades, analog telephony was valued for its simplicity and its ability to keep working through local power outages. But the copper network underneath it is expensive to maintain, and that cost is only becoming harder to justify next to modern fiber and mobile alternatives — a shift the industry commonly calls the copper sunset.
Aging Infrastructure and Rising Costs
Some copper lines in service today are more than a century old. Weather damage, corrosion, general deterioration, and the shrinking pool of technicians who specialize in analog infrastructure all push maintenance costs upward. Providers respond by raising prices, declining new POTS installations, or retiring service in specific areas altogether.
Limited Features
Modern business communication increasingly depends on mobile access, CRM integration, digital messaging, and unified platforms. POTS delivers basic voice and essentially nothing else — no video conferencing, no voicemail-to-email, no intelligent call routing, no business SMS, no call analytics. It can also be prone to line noise and interference that a properly configured IP connection avoids.
Regulatory and Provider Changes
The FCC has given telecom providers more flexibility to retire legacy copper networks and shift customers toward fiber, fixed wireless, and 5G alternatives. There’s no single nationwide shutdown date — availability and timing depend heavily on the provider, the region, and the specific service.
What Replaces a POTS Line?
The right replacement depends on the equipment you’re supporting, how much internet and power resilience you have, and which features your team actually needs.
Cloud VoIP
Voice over IP converts calls into digital data and routes them over an internet connection, supporting desk phones, desktop apps, and mobile softphones. It’s the strongest fit for businesses that want remote and hybrid work support, call routing and auto-attendants, business SMS, video meetings, and centralized online administration.
Cloud PBX
A cloud PBX delivers the call-control functionality of a traditional on-premises private branch exchange — extensions, call flows, schedules, transfers, and voicemail — through a hosted service. It’s a strong option for businesses that want a complete phone system without owning and maintaining PBX hardware, and it also supports phased migrations away from POTS.
SIP Trunking
SIP trunking connects an existing on-premises PBX to a cloud voice network, letting a business keep compatible hardware while replacing traditional analog trunks. This is the natural path for organizations with an existing PBX investment — commonly running on established on-premises PBX platforms — that want a gradual, phased migration rather than a full rip-and-replace.
Cellular and LTE Adapters
Cellular adapters use 4G or 5G networks to deliver a dial tone to compatible analog equipment, which is often the right fit for alarms, elevators, and payment terminals where a standard VoIP phone system isn’t a direct substitute. Always confirm compatibility with the equipment manufacturer, alarm company, or local code authority before installation.
Fiber-Optic Voice Service
Businesses upgrading their internet connection can run voice over the same fiber connection used for data, gaining high bandwidth without the limitations of aging copper — though local power and network equipment are still required to keep the line active.
POTS vs. VoIP: A Side-by-Side Comparison
| Function | POTS | VoIP |
|---|---|---|
| Transport | Analog signal over copper wiring | Digital voice over an IP network |
| Call quality | Stable on a good line; can pick up noise or interference | HD voice available on a well-provisioned network |
| Power | Typically supplied by the phone company | Requires local power for network equipment and phones |
| Outage behavior | May continue during a local power outage | Requires backup power, redundancy, or failover planning |
| Mobility | Tied to a physical jack | Works through desk phones, computers, and mobile apps |
| Call routing | Basic, line-level service | Menus, schedules, queues, transfers, and routing rules |
| Administration | Often requires a technician or provider order | Managed online by an administrator |
| Scalability | New lines often require additional wiring | Users and numbers added through the provider portal |
| Features | Basic calling, limited add-ons | SMS, voicemail transcription, video, team chat, integrations |
Advantages of Moving From POTS to Business VoIP
Beyond simply keeping the lights on as copper disappears, moving to VoIP typically unlocks real operational advantages: support for remote and hybrid employees, local and toll-free numbers that follow the business rather than a wall jack, call routing that adapts to business hours and locations, mobile and desktop apps, business SMS, video meetings, and centralized administration that doesn’t require a technician visit for every change.
Those benefits come with tradeoffs worth planning for. VoIP depends on your internet connection and local power, so a network outage or poorly configured Wi-Fi setup can affect call quality. Before migrating, it’s worth planning for battery backup on routers and switches, a secondary internet connection or cellular failover, proper quality-of-service (QoS) configuration for voice traffic, correctly registered emergency-calling locations, and compatible adapters for any legacy equipment that isn’t moving to IP directly.
How Cytranet Helps With POTS Replacement
Every POTS migration is really several smaller migrations bundled together — a fax line here, an alarm panel there, a payment terminal in the back office — and getting the sequencing wrong is what causes outages and lost numbers. At Cytranet, we start by inventorying every analog line a business depends on, matching each one to the right replacement path, and building a rollout that ports numbers, tests equipment, and confirms emergency calling before a single POTS line gets disconnected.
Whether that means a full move to cloud VoIP, SIP trunking that preserves an existing PBX investment, or coordinating a replacement path for legacy alarm and elevator equipment, our team designs the migration around the equipment you actually have — not a one-size-fits-all cutover.
POTS Line FAQs
What is an example of a POTS line?
A home or office landline is the most common example. Elevator phones, fax lines, payment terminals, and older alarm panels also commonly run on POTS.
Can a business keep its phone number when switching from POTS?
Yes, through a process called number porting. A new VoIP provider manages the transfer of an existing number, and the POTS line should stay active until the port is fully complete.
Are POTS lines being discontinued everywhere?
Providers are retiring copper networks in some regions, but there’s no single nationwide shutdown date. Availability and pricing depend heavily on the provider and location.
Can an old analog phone work with a VoIP system?
Yes. An analog telephone adapter (ATA) converts the signal from a traditional phone into digital voice traffic compatible with a VoIP system.
Can a business keep its existing PBX during a POTS migration?
Yes. SIP trunking connects a compatible on-premises PBX to a cloud voice network, allowing a business to keep its PBX and desk phones while replacing traditional analog trunks underneath it.
