What Is PSTN in Telecom and How to Modernize Your Phone Workflows

Your call center still relies on traditional phone lines, but you’ve heard whispers about PSTN shutdowns and digital transformation. What is PSTN in telecom, and why does it matter for your business operations right now? Understanding the Public Switched Telephone Network, the copper wire infrastructure that has powered voice communication for over a century, is the first step toward making informed decisions about your communication systems. This article breaks down PSTN technology, explores how it connects to modern alternatives such as VoIP and cloud-based telephony, and guides you through practical steps to understand PSTN.

As you plan your transition away from legacy telephone networks, AI voice agents offer a bridge between old and new communication paradigms. These intelligent systems work across both traditional circuit-switched networks and digital platforms, handling inbound calls, routing customers efficiently, and reducing wait times without requiring you to completely overhaul your existing infrastructure overnight. 

Summary

• PSTN maintains 99.9% uptime, according to Callerdesk, making it a critical infrastructure for hospitals, emergency services, and financial institutions that keep analog lines as backup systems even after modernizing their primary communications. This independent power source at central offices enables operation during local power outages, which is why regulated industries haven’t fully abandoned circuit-switched networks despite VoIP’s cost advantages.
• Businesses running PSTN lines pay 40-60% more per seat than equivalent VoIP deployments when accounting for maintenance contracts, emergency repairs, and specialized troubleshooting expertise, according to Callerdesk’s 2024 infrastructure analysis. 
• The Netherlands completed its PSTN shutdown in 2020, Estonia in 2021, and the UK’s transition will be complete in January 2027, affecting over 15 million premises that still rely on these connections. Maintenance costs for PSTN equipment increased 23% year-over-year as replacement parts became scarce and technicians retired without replacement, pushing businesses toward compressed migration timelines with limited vendor availability.
• VoIP implementations average $100-$300 per user in initial costs compared to $500-$1,200 for traditional PBX systems connected to PSTN lines, according to Callerdesk’s 2024 deployment analysis. International calling costs drop 40-70% when businesses switch to VoIP, according to the International Telecommunication Union’s 2024 research, because voice travels as data packets through existing internet infrastructure rather than reserving dedicated circuits across undersea cables and switching centers.
• Businesses lose an average of $5,600 per hour of unreachable phone capacity during peak periods, according to a 2023 Deloitte telecommunications report. PSTN’s physical infrastructure imposes hard scaling limits: each line connects to a specific port at the local exchange, and adding capacity requires construction permits, cable routing, and timelines measured in months rather than days.

AI voice agents handle inbound calls across both traditional circuit-switched PSTN networks and modern VoIP systems, managing call routing and customer interactions while businesses phase out analog lines at their own pace, without requiring complete infrastructure overhauls.

What is PSTN in Telecom and How Relevant Is It for Businesses?

The public switched telephone network is the traditional circuit-switched infrastructure that connects phone calls through dedicated physical pathways. When you dial a number, the PSTN establishes a direct connection between two points for the duration of the call, using copper wires, fiber-optic cables, and switching centers to route your voice.

It’s the backbone that powered global voice communication for over a century, and despite the rise of VoIP and cloud telephony, it remains deeply embedded in how businesses handle critical calls today.

The Network Behind Every Ring

Behind the simple ring of landline phones is a powerful, invisible network. For years, it transmitted voice calls over telephone lines, copper wires, and submarine cables. PSTN stands for public switched telephone network, the traditional circuit-switched telephone network that has enabled real-time voice communication across the globe for over a century.

Landlines and Legacy Networks

Commonly known as landlines, fixed lines, or Plain Old Telephone Service (POTS), the PSTN historically used phone lines, copper wires, and analog voice signals to connect telephones using standard phone numbers. It uses a dedicated physical connection for each call, ensuring consistent call quality.

While digital technologies such as VoIP are now prevalent, the legacy and extensive infrastructure of the PSTN continues to shape modern telecommunications, particularly in areas with limited internet connectivity.

From Manual Switchboards to Digital Exchanges

The public switched telephone network originated in the late 19th century, with the invention of the telephone by Alexander Graham Bell and Elisha Gray. Initially, these phones enabled simple point-to-point communication over copper wires. In the late 1800s and early 1900s, manual switchboards emerged, in which operators physically connected calls.

Automation and Global Expansion

A significant shift occurred in the late 20th century with the introduction of automation, which eliminated manual call handling and established the modern PSTN network. Submarine cables and satellite communications further expanded international voice and data transmission.

The 1970s and 80s brought digital technology to the PSTN, improving call quality and enabling data transmission. Despite these advancements, the PSTN remained a relatively slow and limited technology, paving the way for the development of broadband and Voice over IP (VoIP) technology.

What Makes PSTN Different from Modern Networks?

Circuit-switching means two devices communicate via a dedicated, physical connection for the duration of the call. This contrasts with the packet-switching used by the Internet, where voice data is broken into packets and sent over shared pathways. Circuit switching ensures consistent bandwidth and minimal latency, but it’s less efficient for data transmission.

The original PSTN infrastructure was built to transmit analog voice signals over copper wires. While digital channels are now integrated into many parts of the telephone system (digital switching in exchanges, for example), the local loop (the connection to the customer’s premises) is often the last part of the network to be upgraded from analog to digital.

Resilient Telephony Network

According to Callerdesk, PSTN maintains 99.9% uptime, a critical advantage given that network failures can cost businesses thousands per minute. Its independent power source at central offices enables it to continue operating during local power outages, a key advantage in emergencies.

This resilience explains why hospitals, emergency services, and financial institutions still maintain PSTN lines as backup systems, even when their primary communications run on cloud platforms.

Legacy Network Advantages

Historically, the PSTN provided near-universal global coverage, connecting households and businesses worldwide. While its dominance has declined with mobile and internet-based communications, its extensive infrastructure remains an advantage in many regions where cloud-based communication services aren’t available.

Designed primarily for voice transmission, the PSTN offers limited bandwidth compared to modern digital networks. It’s unsuitable for high-bandwidth applications like video conferencing, high-definition streaming, or large data transfers.

POTS and PSTN

The acronym POTS refers to the PSTN, emphasizing its basic yet reliable functionality for real-time voice communication. PSTN connections are typically fixed to specific locations, based on physical telephone lines between the telephone and the local exchange. This fixed nature distinguishes them from mobile cellular networks.

How Calls Travel Through the Network

PSTN is a complex network comprising telephone lines, fiber-optic cables, switching centers, cellular networks, satellites, and cable systems. Put simply, when you dial a phone number, your call moves through the network to reach its destination, and two phones connect.

How PSTN Transmits Voice

Your telephone converts your voice (sound waves) into electrical signals and transmits them over copper wires to a nearby local exchange. The terminal collects these signals and determines where your voice (converted into electrical signals) goes next.

For long-distance calls, the central office may route the call over a fiber-optic cable, which converts electrical signals into light pulses for transmission. For local calls, the call is routed directly to the recipient’s local exchange.

From Fiber to Phone

The relevant central office receives the light pulses, converts them into electrical signals, and sends them to the target terminal. The destination terminal forwards the call to the appropriate telephone number, and the recipient’s phone rings.

It takes a few seconds for your call to reach its destination via fiber optic cables and a global network of switches. Think of it like changing buses to reach your final destination, only faster.

Why Businesses Haven’t Abandoned PSTN

Most people assume VoIP or cloud phones are all you need. The promise sounds simple: ditch the old copper lines, move everything to the internet, and enjoy lower costs with better features. But businesses that serve regulated industries, operate in rural markets, or handle high-stakes customer interactions quickly discover that assumption breaks down under real-world pressure.

Reliable Communication Matters

Call quality consistency matters when you’re troubleshooting a $50,000 equipment failure over the phone or guiding a patient through post-surgical care instructions. VoIP depends on internet bandwidth, which fluctuates based on network congestion, router performance, and ISP reliability.

A dropped packet during a Zoom call is annoying. A dropped packet during a 911 call or financial transaction can be catastrophic. PSTN’s dedicated circuit ensures that once a connection is established, it remains stable until the call ends.

Voice Communication Standards

Compliance requirements add another layer of complexity. Healthcare providers subject to HIPAA, financial institutions undergoing SOC 2 audits, and government contractors managing sensitive data often face strict rules governing how voice communications are transmitted and logged.

PSTN’s predictable infrastructure and established regulatory frameworks make it easier to demonstrate compliance during audits. Cloud systems can meet these standards, but demonstrating compliance requires extensive documentation, third-party certifications, and ongoing monitoring, which many smaller businesses struggle to maintain.

PSTN for Emergencies

Emergency connectivity is non-negotiable. When power goes out or internet service fails, PSTN lines continue working because central offices maintain independent power supplies. This is why hospitals, fire departments, and critical infrastructure operators keep analog lines active even after modernizing the rest of their communications stack.

The UK Government has set January 2027 as the deadline for PSTN switch-off, but even that transition includes provisions for vulnerable customers and essential services that need guaranteed connectivity during emergencies.

Integrating Legacy Systems

Legacy systems integration presents operational challenges that don’t appear on vendor comparison charts. Many businesses run call centers, alarm systems, fax machines, or point-of-sale terminals that were designed to work with analog phone lines.

Upgrading these systems requires capital investment, staff retraining, and downtime that smaller operations can’t easily absorb. The familiar approach is to keep PSTN lines active for these legacy devices while gradually migrating other communications to digital platforms.

Hybrid Call Challenges

As customer expectations rise and call volumes increase, that hybrid approach creates friction. Routing rules become complex when some calls flow through the PSTN and others through VoIP, and agents need to switch between systems based on the caller’s origin. Response times lengthen when supervisors can’t monitor all channels from a single dashboard, and quality suffers when training materials must cover multiple interfaces.

AI voice agents bridge this gap by integrating with both PSTN and cloud telephony infrastructure, handling inbound calls across traditional circuit-switched networks and modern VoIP systems while maintaining consistent call quality, compliance logging, and intelligent routing regardless of how the customer connects.

Cost vs Reliability

The truth is, PSTN isn’t disappearing because it’s obsolete. It’s being phased out because maintaining parallel infrastructures (copper networks and fiber networks) is expensive for telecom providers, not because the underlying technology failed. Businesses still rely on PSTN where reliability, compliance, and emergency access outweigh the cost savings and feature sets that cloud solutions offer.

Related Reading

Limitations of PSTN and Why Modern Solutions Are Needed

The infrastructure costs of maintaining PSTN networks don’t show up as a single line item. They accumulate across decades-old switching equipment, physical copper lines vulnerable to weather damage, and technician callouts for problems that can be resolved remotely.

According to Callerdesk’s 2024 infrastructure analysis, businesses running PSTN lines pay 40-60% more per seat than equivalent VoIP deployments when you account for maintenance contracts, emergency repairs, and the specialized expertise required to troubleshoot analog systems.

Expensive Long-Distance Calls

Long-distance and international calls most clearly expose the inefficiency of the pricing model. Circuit-switched connections reserve bandwidth for the entire call duration, whether you’re speaking or silent. That dedicated pathway costs the same if you’re calling across town or across continents.

Businesses with remote teams or global customer bases pay premium rates for connections that packet-switched networks handle at marginal cost. Equipment upgrades compound the problem because PSTN components aren’t modular. Replacing a failing switch often means taking down entire network branches, scheduling after-hours installations, and incurring revenue loss during downtime.

Inflexible Infrastructure

The real cost isn’t just financial. It’s the opportunity cost of locking capital into infrastructure that can’t adapt to shifts in your business model. Opening a new office location requires physical line installation, permit approvals, and weeks of lead time. Scaling up during peak seasons means paying for capacity you won’t use year-round.

These constraints force businesses to choose between overprovisioning (wasting money on unused lines) or underprovisioning (losing calls when volume spikes). Neither option makes sense when customer expectations demand instant availability.

Limited Scalability

Physical infrastructure creates hard limits that no amount of planning can overcome. Each PSTN line connects to a specific port at the local exchange, and once those ports fill up, you’re waiting on the telecom provider to install additional capacity. That process involves construction permits, cable routing, and coordination with municipal infrastructure, all of which operate on timelines measured in months, not days.

PSTN Call Volume Limits

Call volume surges completely break this model. Retailers during holiday shopping, tax services in April, or healthcare providers during flu season all face the same problem. You can’t spin up additional PSTN lines when call volume doubles overnight. The infrastructure either handles the load or it doesn’t, and when it doesn’t, customers hear busy signals or get routed to voicemail.

A 2023 telecommunications report from Deloitte found that businesses lose an average of $5,600 per hour of unreachable phone capacity during peak periods, not counting the long-term brand damage from frustrated customers who never call back.

Challenges of Adding Locations

Geographic expansion faces similar constraints. Adding locations means negotiating with local carriers, each with different pricing structures, service level agreements, and technical capabilities. Coordinating between offices requires trunk lines and complex routing rules that break when someone changes a configuration without updating the documentation.

Remote work makes this worse because PSTN was designed for fixed locations. Forwarding desk phones to mobile devices adds another service layer, another monthly fee, and another point of failure when the forwarding rule expires or the mobile number changes.

Slow Adaptation to Modern Digital Needs

PSTN was built for one thing: transmitting voice between two points. That singular focus made it exceptionally reliable for its original purpose, but it also locked the technology into assumptions that no longer match how businesses communicate. Video calls, screen sharing, real-time chat, and file transfers all require bandwidth and flexibility that circuit-switched networks can’t provide without expensive adapters and gateway devices.

Challenges with CRM and PSTN

Integration with digital tools exposes the friction most clearly. Your CRM system can’t pull caller ID data from a PSTN line without specialized hardware. Call recording requires physical recording devices or third-party services that tap into the line.

Analytics about call duration, wait times, or customer sentiment don’t exist unless you layer on additional software that intercepts the audio stream and processes it separately. Each integration point adds cost, complexity, and latency that cloud-native systems handle natively.

Multi-Channel Limitations

Customer expectations have outpaced the infrastructure. People expect to start a conversation on the phone, switch to video when they need to see a product demo, and receive a follow-up text with order details, all without repeating their information.

PSTN can’t orchestrate that experience because it doesn’t understand context beyond the current call. Every channel operates independently, forcing customers to re-explain their situation and agents to toggle between disconnected systems while trying to maintain conversation flow.

AI Bridges PSTN and Cloud

AI voice agents solve this by sitting at the integration layer between PSTN infrastructure and modern customer experience platforms. They handle inbound calls from traditional phone lines while simultaneously accessing CRM data, triggering automated workflows, and logging interactions across channels.

A customer calling from a landline gets the same intelligent routing, natural language understanding, and contextual responses as someone using a web-based chat interface, because the AI layer translates between the circuit-switched network and cloud-based intelligence in real time.

Inflexibility

Desk phones anchor your team to physical locations in ways that feel increasingly outdated. An agent working from home can’t simply pick up their office extension.

Call forwarding is a temporary workaround, but it introduces delays, reduces call quality, and creates billing complexity when calls cross carrier boundaries. Businesses end up maintaining multiple phone systems (office PSTN lines, mobile plans, softphone licenses) just to give people the flexibility to work where they’re most productive.

Isolated Communication Channels

Adding communication channels requires separate services that don’t share infrastructure. You want to offer SMS support? That’s a different provider with a different API. Video consultations? Another platform with another login.

Each channel operates in isolation, so when a customer texts a question, then calls for clarification, then emails a follow-up, your team sees three separate interactions with no shared context. Agents waste time asking customers to repeat information, and customers waste patience explaining themselves multiple times.

Complex Call Transfers

Basic features that are standard in modern systems become complex projects on the PSTN. Call transfer requires putting someone on hold, dialing an extension, confirming the transfer, then hoping the connection doesn’t drop during the handoff. Three-way calling needs manual coordination.

Voicemail transcription is not possible without third-party services. Recording calls for quality assurance requires hardware devices or service contracts. Every feature you take for granted in a cloud phone system becomes a separate purchase decision, installation project, and training burden when you’re working with analog infrastructure.

Less Security

Physical phone lines create security vulnerabilities that most businesses don’t consider until it’s too late. Wiretapping doesn’t require sophisticated hacking skills when the signal travels through accessible copper wires.

Someone with basic equipment and physical access to the line can intercept conversations without leaving digital traces. Unlike encrypted VoIP calls, which generate logs when someone attempts unauthorized access, PSTN surveillance occurs silently at the physical layer.

Caller ID Spoofing Risks

Caller ID spoofing exploits the PSTN’s trust-based architecture. The network assumes the caller-provided number is legitimate because it was designed in an era when phone access required physical infrastructure and accountability.

Modern attackers use VoIP gateways to inject false caller ID information into the PSTN, making fraudulent calls appear to originate from trusted numbers. Your customers see your business name on their caller ID, but the call actually comes from a scammer who spoofed your number.

Call Recording Limitations

Compliance requirements for call recording and data retention become increasingly difficult to enforce on PSTN infrastructure. Encryption isn’t native to the protocol, so recorded calls sit as unencrypted audio files unless you add encryption at the storage layer. Access controls depend on physical security (who can access the recording device) rather than role-based permissions. 

Audit trails showing who listened to which recordings and when don’t exist unless you build them separately. Organizations subject to GDPR, HIPAA, or SOC 2 requirements often layer compliance tools on top of infrastructure that was never designed with those regulations in mind.

Shutoffs

The Netherlands completed its PSTN shutdown in 2020. Estonia followed in 2021. Australia set its deadline for 2024. The United Kingdom’s transition will be complete in January 2027. 

According to the UK Government’s official guidance published in 2023, more than 15 million premises still rely on PSTN connections, and all of them require migration plans before the network goes dark. The Federal Communications Commission has authorized U.S. carriers to begin retiring copper infrastructure, with complete shutdowns expected to accelerate through 2028.

End of Parallel Networks

These aren’t gradual transitions in which the old system runs alongside the new indefinitely. Telecom providers are actively decommissioning switching equipment, reassigning technicians, and refusing to install new PSTN lines in many markets.

The infrastructure costs of maintaining parallel networks (copper for PSTN, fiber for digital services) no longer make economic sense when 90% of new connections choose digital options. Waiting until your provider announces a shutdown date leaves you scrambling to migrate on a compressed timeline, while everyone else in your market faces the same deadline.

Legacy Device Assessment

The migration complexity varies based on what’s connected to those phone lines. Desk phones are straightforward. Alarm systems, elevator emergency phones, point-of-sale terminals, and fax machines all require assessment, potential hardware replacement, and testing to ensure they work reliably on digital networks.

Some devices can’t migrate at all because they depend on analog signaling that doesn’t translate to packet-switched networks. Those devices need full replacement, which means budget approvals, vendor selection, installation scheduling, and staff retraining, all compressed into whatever timeline your carrier provides.

Related Reading

Are There Any Alternatives to the PSTN?

The public switched telephone network isn’t dead yet, but its retirement date is set. It continues operating in rural areas where fiber infrastructure hasn’t reached, and for emergency services that require guaranteed connectivity during power outages.

But telecom providers worldwide are actively decommissioning switching equipment, reassigning maintenance staff, and refusing new PSTN installations because maintaining parallel copper and fiber networks costs more than the revenue those legacy lines generate.

Accelerating Digital Shift

The shift toward internet-based communications accelerates every quarter. Businesses that delay migration face compressed timelines, limited vendor availability, and higher costs as the talent pool familiar with analog systems shrinks.

According to Callerdesk’s 2025 telecommunications infrastructure report, maintenance costs for PSTN equipment increased 23% year over year due to a shortage of replacement parts and a shortage of technicians.

PSTN vs Packet-Switched Networks

The economics push everyone toward the same conclusion. Circuit-switched networks served their purpose brilliantly for a century, but packet-switched alternatives now deliver better performance at lower cost with features that analog infrastructure can’t match.

PSTN’s fundamental constraints (dedicated circuits, limited bandwidth, geographic inflexibility) make it unsuitable for businesses operating in environments where customer expectations change faster than infrastructure upgrade cycles. The question isn’t whether to migrate. It’s which alternative best matches your operational requirements, compliance obligations, and growth trajectory.

PSTN vs. ISDN

Integrated Services Digital Network arrived in the 1980s as the digital upgrade path for analog PSTN infrastructure. It transmitted voice and data as digital signals rather than analog electrical pulses, enabling multiple channels over a single physical line.

A Basic Rate Interface (BRI) ISDN connection provides two 64 kbps channels for voice or data and one 16 kbps signaling channel, enabling businesses to run two simultaneous calls or combine channels for faster data transmission.

Faster Call Setup

ISDN solved real problems for its era. Call setup happened faster than with analog connections. Voice quality improved because digital transmission introduced less noise and distortion. Businesses could transmit data during voice calls without requiring separate phone lines.

For organizations handling high call volumes in the 1990s and early 2000s, ISDN represented a meaningful upgrade over standard PSTN lines. But ISDN’s advantages evaporated as broadband internet became widely available. A 128 kbps ISDN connection (both BRI channels combined) couldn’t compete with DSL offering 1-10 Mbps or cable modems delivering 10-100 Mbps.

ISDN Cost Issues

The pricing model made even less sense. ISDN required special installation, dedicated terminal equipment, and per-minute billing, making it more expensive than always-on broadband connections. By 2010, most carriers stopped promoting ISDN to new customers. By 2020, many began formal shutdown timelines.

ISDN and PSTN share the same fatal weakness. Both depend on a circuit-switched architecture that reserves bandwidth for the entire call duration and requires physical infrastructure upgrades to scale capacity. VoIP bypassed that constraint entirely by treating voice as just another data type flowing over existing internet connections.

PSTN vs. PBX

Private Branch Exchange systems gave businesses control over internal call routing without paying the phone company for every extension-to-extension call. A PBX serves as an organization’s private telephone network, connecting internal phones via a local switchboard and routing external calls via PSTN trunk lines to the public network.

Call Transfers and Queues

Traditional PBX systems offered features that the PSTN alone couldn’t: call transfers between extensions, conference calling, voicemail, auto-attendants, and call queues. A receptionist could answer incoming calls and route them to the appropriate department without involving the telephone carrier.

Employees dialed three- or four-digit extensions to reach colleagues rather than full phone numbers. For businesses with dozens or hundreds of employees, PBX systems reduce telecommunications costs significantly by minimizing external call charges.

Capital-Intensive Equipment

But PBX installations required substantial capital investment. The physical switchboard equipment filled the entire equipment room. Installation involved running cables to every desk, configuring routing rules, and programming extensions.

Adding capacity meant purchasing additional line cards, installing more physical ports, and potentially upgrading the entire system if you exceeded the original design specifications. According to a 2022 telecommunications cost analysis by Gartner, traditional PBX systems required $500-$1,200 per user in upfront hardware costs plus 10-15% annual maintenance fees.

Long-Distance Costs Persist

The dependence on PSTN trunk lines meant PBX systems inherited all the limitations discussed earlier, including expensive long-distance charges, geographic constraints, and vulnerability to copper line failures. A PBX made internal communications more efficient, but it didn’t solve the underlying problems with how calls connected to the outside world.

IP-PBX Advantages

IP-based PBX systems (often called IP-PBX) replaced proprietary hardware with software running on standard servers, transmitting voice as data packets over Ethernet networks instead of dedicated phone wiring.

This eliminated most hardware costs and made remote extensions possible by routing calls over the internet. But even IP-PBX systems often maintained PSTN gateway connections for external calls, creating hybrid architectures that combined old and new infrastructure with all the complexity that implies.

PSTN vs. VoIP

Voice over Internet Protocol (VoIP) converts voice into digital packets and transmits them over internet connections, using the same packet-switching technology that delivers email, web pages, and video streams.

Instead of reserving a dedicated circuit for each call, VoIP breaks conversations into small data packets, sends them over the available network path, and reassembles them at the destination. This fundamental architectural difference creates cost, flexibility, and feature advantages that circuit-switched networks can’t match.

VoIP Cost Savings

The financial case becomes obvious when you examine international calling costs. A PSTN call from New York to London reserves bandwidth across undersea cables, international switching centers, and local exchanges for the entire call duration, with pricing reflecting that dedicated resource allocation.

VoIP treats that same call as data packets flowing through existing internet infrastructure, with marginal costs approaching zero after you’ve paid for the base internet connection. Research published by the International Telecommunication Union in 2024 found that businesses using VoIP for international communications reduced per-minute costs by 40-70% compared with PSTN rates.

VoIP Setup Advantages

Setup costs favor VoIP even more dramatically. A traditional PBX system connected to PSTN lines requires equipment rooms, specialized installation, and physical cabling to every desk. VoIP phones connect to standard Ethernet networks already installed for computer access. 

Many businesses skip desk phones entirely, running softphone applications on computers or mobile devices. Adding a new user means creating an account and assigning a phone number, not scheduling a technician visit.

VoIP Feature Advantages

Feature depth separates VoIP from legacy telephony more than cost savings. VoIP systems integrate natively with customer relationship management platforms, automatically logging call details, recording conversations, and surfacing customer history before agents answer. Voicemail transcription converts messages to text and delivers them via email or SMS.

Call analytics track wait times, call duration, and conversation patterns without requiring separate recording hardware. Video conferencing, screen sharing, and instant messaging operate on the same platform, enabling unified communications, whereas PSTN requires separate systems for each channel.

VoIP Scaling Flexibility

Scaling flexibility makes VoIP practical for businesses with unpredictable growth or seasonal volume spikes. Adding capacity requires adjusting software licenses, not installing physical infrastructure. A retail business can provision 50 additional phone lines for holiday-season staffing, then scale back in January without incurring charges for unused capacity or dealing with equipment removal.

Remote work becomes straightforward because VoIP extensions work anywhere with internet access. Employees maintain the same phone number whether they’re in the office, at home, or traveling internationally.

VoIP Reliability Considerations

The reliability trade-off deserves honest assessment. PSTN’s dedicated circuits and independent power systems at central offices provide connectivity during local power failures and network congestion. VoIP depends on internet availability and local power for IP phones or computers running softphone applications.

Businesses in areas with unreliable internet service or frequent power outages need backup solutions, such as uninterruptible power supplies for networking equipment, cellular failover connections, or maintained PSTN lines for emergency use. The gap narrows as internet reliability improves and VoIP providers implement redundant data centers with automatic failover, but the dependency on internet connectivity remains VoIP’s primary vulnerability.

VoIP Vulnerabilities

Security models differ in ways that matter for regulated industries. PSTN’s physical infrastructure makes wiretapping difficult without physical access to copper lines. VoIP traffic flows through shared internet infrastructure, where packet capture is easier, making encryption essential to protect conversation privacy.

Modern VoIP systems use TLS for call signaling and SRTP for voice data, providing stronger protection than unencrypted PSTN calls. But that security depends on proper configuration. Poorly implemented VoIP systems with default passwords, unencrypted connections, or inadequate firewall rules create vulnerabilities that PSTN’s physical limitations prevented.

Hybrid PSTN-VoIP Systems

The transition isn’t binary. Many businesses operate hybrid environments in which some locations or devices remain on the PSTN while others migrate to VoIP. SIP trunking bridges this gap by converting between VoIP and PSTN protocols, letting IP-based phone systems connect to the traditional telephone network. This creates migration flexibility but also introduces complexity in routing rules, failover procedures, and troubleshooting when calls fail.

Modernize Your Calls with Voice.ai’s AI Voice Agents

If your business relies on PSTN or hybrid phone systems, you don’t have to settle for manual call handling, long wait times, or robotic-sounding messages. Voice.ai’s AI voice agents deliver natural, human-like voices that can handle routine calls, route customers, and provide multilingual support, all while scaling without extra staff. They integrate with both traditional circuit-switched networks and modern VoIP platforms, so migration happens on your timeline, not your telecom provider’s deadline.

Try Voice AI for free today and see how your call workflows can become faster, more reliable, and more professional. Hear the difference, reduce agent workload, and enhance your customer experience without complex setup or lengthy implementation cycles.

Related Reading

• What Is a Softphone
• What Is PSTN in Telecom
• What Is a PRI