A cloud-based PBX (Private Branch Exchange) system is a virtual phone system that operates over the internet rather than through traditional on-premises hardware. It allows businesses to manage inbound and outbound calls, route calls to different departments or employees, and access features like voicemail, call forwarding, and auto-attendants — all from the cloud. Cloud-based PBX systems are scalable, cost-effective, and accessible from anywhere with an internet connection. Many companies integrate these systems with platforms like Phonexa to enhance call tracking, lead management, and performance analytics for better customer service and marketing outcomes.

**Cloud-based PBX system**

So, firstly I would like to share **what is cloud **? After that, I will explain a Proper understanding of cloud-based PBX and How it is helpful for our business.

Before a Days users and companies do not have to manage physical servers themselves or run software applications on their own machines. so companies need more space and storage to manage everything that time we need Cloud platform .

Nowadays everything is on the cloud whether it is including servers, storage, databases, networking, software, analytics etc. so why we are not save our business communication through the cloud-based PBX system. so that time we need a cloud-based PBX system to manage everything of our whole business.

Advantages:

1. we can manage business calls, meetings, discussion ,voicemail, call forwarding etc.
2. level-up your workflows
3. Flexibility for all locations and seasons
4. Worry-free reliability and uptime
5. No maintenance
6. Cost-effective for all companies.
7. Time Saving

Two key differences are cost and flexibility. Traditional PBX phone systems require a heavy investment in hardware. In addition to the costs of buying and setting up the telecom equipment, the providers have to cover the costs of all that copper wiring connecting clients with the exchange. The expenses do not cease with installation since these systems also require continual maintenance. System upgrades also necessitate buying and installing new equipment. All of these expenses need to be taking into account when setting realistic prices to charge the clients.

This reliance on fixed equipment limits the flexibility of traditional PBX system providers to quickly respond to changing customer requirements. For example, adding lines or activating new features necessitates sending out a phone engineer to the customer premises. There are also usually extra charges for upgraded phone equipment.

IP PBX systems do not have all of these big hardware expenses. They transmit calls over the existing internet infrastructure. Customers can use VoIP phone systems on their smart phones or computers - they do no need to pay for any special phone equipment. When they want to add new lines or activate other features, they do not need to call out an engineer. The customer can make these changes via the provider’s website. The lower costs of VoIP systems enable the providers to significantly reduce charges to their customers. The greater flexibility is another attractive factor as it gives the customer the ability to customize their business phone system.

An IP phone system is a telephone system that uses the internet to make and manage calls instead of traditional phone lines. It stands for Internet Protocol Phone System, and it's a modern way to handle business communications.

Now, let’s break down what an IP PBX telephone system is:

✅ What is IP PBX?

IP PBX stands for Internet Protocol Private Branch Exchange. It is a business phone system that:

• Connects internal phones within a company
• Routes calls using the internet (VoIP - Voice over Internet Protocol)
• Replaces old traditional PBX systems that used landlines

🧩 Key Features:

• Call Routing: Directs calls to the right person or department
• Voicemail: Lets users receive and manage messages easily
• Auto Attendant: Answers calls and provides menu options
• Call Recording: Records calls for training or quality checks
• Conference Calling: Allows multiple people to join a single call

💡 Benefits of IP PBX:

• Cost Savings: Cheaper than traditional phone systems
• Scalable: Easy to add or remove users as your team grows
• Remote Access: Works well for remote or hybrid teams
• Advanced Features: Like voicemail to email, call forwarding, and more
• One Network: Uses your internet connection for voice and data

🏢 Who Uses It?

• Small to large businesses
• Call centers
• Companies with multiple offices or remote workers

In simple terms, an IP PBX system is a smarter, internet-based phone system that helps businesses handle calls more efficiently while saving money.

Yes, as mentioned before, there is more to know before a real answer can be given.

Decide on wants and needs for now and the (near) future. Then decide on your budget (and possibly a stretched budget in case you need it so that you can obtain some critical functions you would otherwise miss). Then decide if you have the knowledge, time and resources to set up, maintain and secure an IPPBX on location.

These 3 should already give you a sort of scope and will decide whether an IPPBX on location is a good idea (which it often isn’t) or if Hosted is the better, easier and cheaper option. Then compare the option to your wants and needs and you’ll lose more possible solutions.

Hopefully, you will then stay with or more solutions that fit in your budget but if not, you know you have to start again but change 1 or more parameters so that you get different results and options.

It isn’t always an easy process so good advice is essential. Although you may be able to change relatively easy, if you need to, if the future proves you should have gone for another option, we tend to see many don’t do so all that easily. So be prudent in your costing, functions, needs and research and go for a solution that fits the bill best and do make sure that their support is as good as you need it to be as they will be your lifeline if something does go wrong.

I hope this helps (or reach out and we may be able to help more).

Best of luck

There are a number of points to make. Here are a few.

1. Ports. On a traditional PBX you are physically limited by the PBX as regards the number of handsets, and incoming lines. You are limited to a specific number of incoming voice channels. An IP PBX is not so limited though you will need a faster processor and more memory as you build out. The only real constraints are those and the license cost you pay to the Software vendor.
2. Sound quality. There’s no audio clipping of the range of the audio. (There isn’t in digital phones connected to a digital wire service either, but it’s at least as good or better with IP PBX’s)
3. Remote handsets. You are note ‘place-bound.’ Your PBX could be in NYC and you could have ‘internal extensions,’ (handsets,) in LA, or London, or, like mine, in the Philippines. My PBX was in Cheyenne, WY and my extension at my desk was in General Santos City, Philippines.
4. Cost per truck. Commercial SIP service provider trunks are 20% of the cost of traditional digital trunks and 15% of the standard POTs line.

PBX phones, the traditional landlines, which have in use for centuries, but with the recent developments, and role of the internet in our lives, the telecommunication systems have enhanced their interaction modules to IP PBX systems. Well, the IP PBX systems, are the upgraded version of the traditional PBX systems, helping the businesses to facilitate local, national, and international communication in an effective manner. These systems provide the organizations with affordable solutions, as the name suggests IP, which means data is transmitted over the internet, which directly makes it a lucrative form of communication, unlike the traditional phones that use the conventional form of voice transmission.

The difference between PBX and IP PBX phones is listed below:

Single Network

Traditional PBX requires its own network, which is an expensive module to build up a telecommunication business infrastructure that will work as a perfect network system for the organization.

IP PBX phones are easy to install and set up, which can be used to transfer voice calls in conjunction with data as well as the VoIP phones that help you to directly connect to network ports by using cables.

Long-Distance Calls

Traditional PBX works just like the landlines, which works over the telecommunication module, making the national and international calling as an expensive process.

IP PBX phones work over the internet, which makes long-distance calls easy and cost-effective step. You can easily terminate SIP calls directly to the IP PBX network.

Voice Transmission

Traditional PBX phones are the conventional phone lines that use copper lines for voice transmission. These systems are designed to handle how the telephone systems work, helping you to make internal calls, which can be linked to the trunk line in order to make external calls.

IP PBX phones run over internet protocol, which does not require any trunk lines, copper lines, or additional hardware for functioning. With the help of the VoIP module, you only need an internet connection that will help you make the calls securely, as the data is transmitted in packets, which directly ensure safe voice transmission.

Your question is too open ended.

• Are you asking about the planning, purchasing, programming?
• Are you asking about deployment when all that above is done?

When moving from a traditional PBX to and IP PBX, the first part happens while the traditional PBX remains in place and is working. Everything should be ready to be dropped in, preprogrammed, before you do the actual install.

• Are you retaining the traditional trunk lines from the current telco, or are you migrating to IP trunking right away?
• This is of critical importance.
• If the IP portion is in-house only, then you (potentially) do not have to coordinate with the Telco. (However if you don’t know the version of public switch and the related values needed to sync up your new hardware with the existing PRI T1/E1 you may still need to talk to the telco.)
• If you are moving to IP trunking, the question of moving the telephone numbers [TN] to the IP trunks becomes a timing issue. I will assume you want to hold on to your existing TNs. That will require forwarding and temp IP TNs until the company TNs migrate to the new trunks. This requires coordination from both the exiting TN provider and the new IP trunking provider.
• Have you built out the network wiring and switching beforehand, or are you doing it at the last moment?
• VoIP can swamp some switches, even good ones from reputable companies. VoIP creates small packets, but a lot of them. Many switches get overwhelmed and can bog down, even though the actual bandwidth is not a lot heavier.
• Do you have the additional electrical outlets at each desk, if needed?
• Have you developed a plan to train staff on how to use the new system?
• Will some of that be before the installation?
• Will you provide written guides to staff on navigation in the new PBX.

With proper planning, preconfiguring, rebuilding your IP wirings and switching, coordination with the telcos regarding forwarding numbers while you implement the moving of the TNs, and sufficient staff, the entire switch from traditional to IP-PBX can happen over a weekend, or even faster.

But the planning before the replacement takes time. The length of time is based on the size and complexity. While complexity adds far more than arithmetical growth of timeframe, it is less than logarithmic. Complex PBX installations will result in a far longer planning and programming time prior to the forklift replacement on ‘installation day.’

There is a subtle, yet importance difference between PBX and PSTN.

First let’s define each:

What is PSTN?

• PSTN stands for Public Switched Telephone Network and is just a fancy name for the traditional telephony we are all familiar with – where telephones are connected to dedicated networks.
• As long as you know the correct telephone number, these networks allow you to call another person anywhere on the network. It’s also commonly referred to as POTS - plain old telephone system.
• Getting more technical - PSTN is the collective switches and all the infrastructure (telephone lines, fiber-optic lines, and underground cables) that make up phone access across the world.
• The PSTN is also further connected by Tandem Offices, and Toll Offices which increase the range of calls at a further cost. These allow for Long-Distance, and International Calls to take place.
• On that point, this is also why most businesses prefer to use VoIP, so that they don’t get hit with long distance overage charges, especially for making international calls.

What is PBX?

• PBX means Private Branch Exchange and is the “switch” in an organization’s premises that routes calls internally and externally to the PSTN/POTS.
• In very plain terms, PBX is the software or hardware solution that manages phone calls for a building or campus.
• The PBX system tells every phone on-site what their extension number is, and routes calls based on phone number, if the location has more than one.
• A PBX may have other features as well - such as hosting an automated attendant, playing hold music, managing all internal calls, building groups of phones that ring simultaneously, and even queueing calls for a call center.

So, what’s the difference between PBX and PSTN?

• The surprising answer is mostly in the scope. Both are switching services that move calls to their final destination. This can be done using software, or hardware solutions.
• The main difference is that PSTN does what a PBX does, but over a much wider area - essentially, it finds the best route to send signals to connect a call.
• The longer the distance of the call, the more bounces the PSTN needs to make to ensure the call gets to its destination. This is routed through various exchanges. These ones aren’t private, but represent different localities in much the same way that a PBX represents a building or campus.
• This is why 7 digit dialing works, it doesn’t need the area code as the local exchange doesn’t need to send the call outside its purview. Like a more expansive extension number.

A cloud-based PBX (Private Branch Exchange) system is a modern telephony solution hosted over the internet rather than traditional on-premise hardware. It offers businesses a flexible, scalable, and cost-effective way to manage their internal and external communications.

Key Features:

• VoIP Technology: Utilizes Voice over Internet Protocol (VoIP) to make and receive calls over the internet.
• Scalability: Easily add or remove phone lines and features based on business needs.
• Cost-Efficiency: Reduces upfront costs by eliminating the need for expensive hardware and maintenance.
• Flexibility: Allows employees to make and receive calls from anywhere, supporting remote and hybrid work environments.
• Advanced Features: Includes auto-attendant, call forwarding, voicemail-to-email, call recording, and more.

Top Cloud PBX Provider: TeleCMI

TeleCMI is a leading provider of cloud-based PBX systems known for its comprehensive feature set, reliability, and user-friendly interface. Here’s why TeleCMI is a top choice for businesses looking to adopt cloud PBX:

Why TeleCMI?

• Easy Setup & Use
• Cost Effective
• Most Secure Platform
• Disaster Recovery
• User-Friendly Interface
• Seamless Customer Support

PBX (private branch exchange) have traditionally been service the role of local telecommunication switches in companies for fixed wire lines.

PBX have evolved over time and have supported IP phones, and remote deployments with hosted PBX.

It then got into the cloud with Cloud PBX.

The last evolution are end to end cloud telephony systems, with no physical infrastructure, see Ring4, RingCentral, Sideline, 8x8, Grasshopper

This is a telephone device used in large houses and commercial premises to distribute phone calls. It will normally have two or more incoming phone lines and a number of extensions. When a call comes in, the PBX will direct the call to which ever extensions have been programmed to ring. You can have different phones ring at different times of the day, so in the day time, the reception phone will take all calls whilst at night, when the receptionist is away, all phones will ring.

These days you can often add both analogue and IP (VOIP) line to a PBX, such as the Panasonic NSP-700:

KX-NS700 - Communication Solutions

In the case of the company I worked for, several years.

Most of the time was taken in designing and redisgning the specification to suit our working practices, and much time after installation trying to make it work properly (which they never did).

I don’t know the name of it, but it was absurdly expensive and was plagued with dropped calls, silent calls, misrouting, poor audio, echo and the worst hold music you can imagine (customers complained about it!). The advantage - the only advantage that I was aware of - was that because it linked all the company’s offices all over the world, it saved them having to pay international rates when calling overseas.

All calls, even internal, were routed through the PABX company’s servers in Germany, regardless of where they were being made to or from. This was over the public internet (on a secure link) so we were at the mercy of our ISP’s reliability - and general network congestion.

An IP PBX is a phone system that operates over the Internet (or Internet Protocol, “IP”) as opposed to traditional analog phone lines. IP PBXs generally cost less and provide as good or better quality as traditional landlines, plus they’re typically capable of providing advanced phone system features like mobility, call routing, conferencing, and more.

Regards, Saahil A Khan |→> One Thought | Saahil A Khan

PBX Phone

PBX is the private branch exchange used to operate in a virtual environment and keeps you connected anywhere - landline, VoIP phone or cell phone. In this technologically advanced world, this quality answering service system works with fax machines, modems and other facilities. It has the in-built capability to recognize speech and interactive voice response. With a full-featured PBX phone system, you get benefits such as automatic call distributor, auto dialing, auto attendant, call pick-up, call transfer, call park, call waiting, call forwarding, conference call, find-me follow-me and customized abbreviated dialing. Through the web interface, you can control and maintain features online.

All voicemails are collected and sent to the email box for further reference. Thus it is possible to handle multiple telephone calls. The service is provided through high bandwidth Internet connection or phone lines. You only need to pay only for the quality answering service you utilize.

PBAX Phone

The users of a PABX system will share several external lines for making external phone calls. A PABX system would also connect the internet telephones within a business and connect them to the public switched telephone network, or PSTN. A recent development in PABX systems is the VolP PBX, also known as IP PBX, which uses the internet protocol to transmit calls.

A PABX system is a frequently used term to describe a private branch exchange, a telephone exchange serving one business. Initially, the PBAX system allowed businesses to control their phone systems using in-house operators. Now, instead of merely connecting voice calls, these systems also connect other types of technology such as fax machines and computer modems that route through phone lines.

The Pros & Cons of Cloud PBX vs. On-Premises PBX Systems

What is a Cloud PBX?

A cloud PBX, better known as hosted PBX, is a business phone system that runs over an internet connection. You don’t need to have Private Branch Exchange (PBX) equipment in your location — a VoIP provider does it for you

.

What is Onsite PBX?

Onsite or On-premise PBX is the traditional PBX phone system. In these phone systems, all the hardware is present at the physical location. Calls made through the on-premise PBX goes through your call server over a dedicated voice network connection.

While initially, it may seem that on-premise PBX is a good option, it has its fair share of disadvantages. Onsite PBX incurs high installation charges. It also requires full-time maintenance. In addition to this, the onsite PBX needs service and support from an in-house IT team.

Cloud PBX vs Onsite PBX

By now it is clear that opting for a cloud based PBX is a better choice as you will be able to reap more benefits when compared to onsite PBX. However, while making your decision to choose between the two, it is important to consider various factors. Here are some pointers to help you :

• Does your IT staff has the technical skills to manage an on-premise communication set up?
• What will be your budget and preferred pricing model?
• Do you have offices in multiple locations or remote workers?
• Will your existing systems integrate with the new communication system?

In accordance with the ongoing trends and market scenario, for most of the businesses, Cloud PBX is the way to go. Going forward, we will understand the benefits offered by these systems.

Essentially, a cloud PBX provides all the functionality needed in an office phone system such as voicemail, call forwarding, and of course, calling. Instead of setting up a server you have to maintain, you’d use a VoIP provider for your company’s communications.
When your staff answers or places calls, VoIP handsets convert the sound into data packets. These packets travel over the internet to the hosted PBX provider. The provider establishes a clear calling path between both parties. When needed, hands off to the Public Switched Telephone Network (PSTN).
Once data packets reach their destination, the business phone system converts them back into sound. It does all this within milliseconds without any extra configuration. See this diagram below to visualize the process. Here’s a diagram for what it would look like for a single office.

All you need is a reliable broadband connection to use a cloud-based PBX. The underlying technology accepts all kinds of IP phones, including desk phones, smartphones, and conference phones.
There are some practical business benefits you should know before getting a free quote.

Advantages of a Cloud PBX

1) Powerful features level-up your workflows

There are many more built-in VoIP features offered by a hosted PBX compared to an on-premises PBX phone system. These advanced features are the ones stakeholders care about most. Expect them to show up on a VoIP requirements list.
Several of the top cloud PBX features include:

• Mobile device support (mobile apps)
• Voicemail to email transcription
• Auto attendants (call flows)
• Automatic call recording
• Intelligent call forwarding
• Built-in video conferencing
• Inbound call queuing

Company leaders will appreciate that there are dozens of VoIP features available that don’t require any technical setup. Your phone system can also integrate with other essential tools like your organization’s CRM.
These added capabilities mean you can get more work done with enhanced productivity.

2) Flexibility for all locations and seasons

A flexible phone system means it can adapt to the changing conditions in the workplace. You can customize your phone system around your business needs versus feeling constrained by an old PBX.
There’s nothing more frustrating as an IT manager than unexpected business changes. You can say yes when the boss asks you if it can be done — without coming in on Saturday.
Small businesses enjoy total control over their company’s phone system. It’s easy to add and assign business phone numbers to your team. It’s even easier to equip your remote team with phone service.
In the era of remote work, employees can stay connected with a robust VoIP softphone app. Alternatively, you can have them take their office desk phone home.
When you increase demand, such as holiday sales, a hosted PBX will allow you to increase your call capacity. Plus, you can add hold music and comfort messages in minutes. This way, you can bump up your call quality and customer satisfaction.

3) Worry-free reliability and uptime

What’s the cost of downtime for your business? From tarnishing brand trust to losing revenue and sales, you can’t afford to deal with outages.
Luckily, a cloud PBX keeps you always reachable. A reputable service provider will offer 99.999% uptime, which is the gold standard for enterprises. Read what customers have said about them on social media, such as Twitter. You’ll get a sense of the reliability provided by the cloud PBX provider.
This increased reliability is made possible thanks to a redundant network of eight separate data centers. VoIP can work even during a power outage. You can route calls to different locations, including mobile phones, within seconds. On the flip side, a traditional phone system can crash due to weather, power failures, and other disasters.
Nextiva has invested millions into building one of the largest, most reliable business VoIP networks nationwide. Even if one of our data centers goes offline, there are seven more to handle the calls.
Related: Is VoIP Reliable? Nine Helpful Tips You Must Know

4) No maintenance

Lack of maintenance is a tremendous advantage of cloud PBX systems. System updates, network routing, adjusting VoIP codecs — it’s all handled by the hosted provider.
IT leaders and CIOs deal with a lot of fires throughout the week. (We hear you!) You can empower select people to make changes to your phone service online. Today’s VoIP phones are hassle-free, so it means fewer helpdesk tickets.
The problem with on-premise PBX systems is maintenance doesn’t stop when you hire full-time support. Having a technician available at all times is great, but you have to budget for $74K annually.
Businesses today have to get more done with less. It’s why switching to a cloud solution is a sensible investment. Get ready to say goodbye to a bulky on-prem communications system and costly VoIP maintenance contracts.

5) Unparalleled security

Cloud PBX phone solutions offer higher security compared to traditional PBX. When you have a physical landline, it’s up to you to ensure no one gains access to it. Many PBX systems are vulnerable to outside attacks, and audio signals they transmit are much easier to intercept.
Some hosted PBX solutions offer call encryption and 24/7 server monitoring. VoIP providers are consistently validated by third parties to check for compliance. VoIP security also means there’s the benefit of certifications like ISO/IEC 20071, PCI compliance, and HIPAA compliance.
Voice over IP itself is both reliable and secure, thanks to the redundancies of IPv4 routing. Encrypted voice packets and signaling works by using TLS and SRTP protocols.
Simply put: A cloud PBX lets you sleep at night. The backbone of your business communications is secure and resilient to bad actors.
Related: VoIP Hacking: How It Works & How to Protect Your VoIP Phone

6) Cost-effective for all companies

You’ll save a ton when you upgrade to VoIP service. Compared to a traditional PBX, premium features are either included or available for a low cost.
The team at Rackspace studied the total cost of ownership of cloud-based solutions. For every $1 spent on hardware upgrades, companies can expect to pay $2 for maintaining and securing that infrastructure.
This statistic should be alarming. On-prem voice equipment can cost you twice as much as you think. Make sure you think about the additional, indirect costs beyond the list price.

Here are the areas where a hosted PBX can lower costs:

• Workforce: Unless you’re a pro at SIP trunking, you’ll want dedicated IT staff or at least on-call IT support.
• Equipment: Use the equipment you already have, such as softphones. You can also rent VoIP phones for lower upfront costs.
• Maintenance costs: You won’t need to pay extra for software, security patches, or firmware updates.
• Adding phone lines: New employees and departments don’t have to wait to get calling.
• Calling costs: Enjoy the freedom of unlimited nationwide calling and low-cost international calls. Likewise, you can block international calling as well.

These cost savings add up. Sure, the switch might be a bit of work, but the payoff is immediate. It’s not hard to understand why over 100,000 businesses have already switched to Nextiva.

While cloud PBX is close to hosted PBX, it's not exactly the same thing. It has the following characteristics:

• The provider is operating servers in the cloud. This means that there is no physical off-site location where servers and other equipment are housed.
• To access the service, a direct network connection is required. Just like other cloud-based services, PBX is accessed through the Internet.
• It's scalable, man. The cloud provides much more flexibility when it comes to scaling up or down services.
• Spikes in demand can have an impact on the service. Since it is difficult to anticipate and handle unexpected demand, high demand can impact other users on the network.
• Capacity of storage can be reduced. Depending on the number of users, the available storage space can be used quickly.
• Typically it's pay-per-use. Instead of charging for a number of users, cloud-based PBX is typically billed for how much you use it.

Basically, If you talk about an On-premise PBX system. which is not connected to a data network. you have to maintain its power supply and data storage by yourself. Also, it’s way more cost-effective in comparison with the VoIP calling system. It’s very reliable with scalability, monitoring on a single click up to 60+ business communication features at 99.99 uptime speed because it’s not dependent on a centralized power supply we are having multiple data centers just to give an HD calling experience all the time.

PBX stands for Private Branch Exchange. It refers to a telephone switching system of an enterprise. It is used to switch calls between VoiP (voice over Internet Protocol or IP) users on local lines to facilitate internal communication of a business. Its main function is to allow in-house calling between extensions and to allow routing for outside calls. For example, when an employee makes a call to another employee on the same network, the call is routed through the PBX without requiring an outside line. He can also make a call outside the company network through the same exchange.

PBX allows companies save costs and improve efficiency, e.g. If a company doesn?t use a PBX, it might need to install 500 separate lines if it has 500 employees. PBX is owned and managed by the company; the telephone exchange does not control it. Earlier, PBX was based on analogue technology, but today, it uses digital technology.

Thanks for reading my answer. Suggestions are always appreciated. Dream Builder Yash Gorani hope it helps.

Private Branch X-change (PBX)

Public Switched Telephone Network (PSTN)

The PBX is a private Electronic telephone switch that is normally housed within the business premises or a home/SOHO. It is generally used for internal communication (INTERCOM) within the building.

The Public Switched Telephone Network on the other hand is a network of Telecom switches (High capacity PBX like switches) that switches public calls. Take it like PBXs that belong to different service providers but they are interconnected and each has it’s own extensions. The extensions in this case are the subscribers to each of these telcos.

In a nutshell, the PBXs that sit in business premisses or homes are in most cases connected to the public switched network to enable the extensions make and receive calls from the public.

1. PSTN

PSTN stands for Public Switched Telephone Network and is just a fancy name for the traditional telephony we are all familiar with – where telephones are connected to dedicated networks. As long as you know the correct telephone number, these networks allow you to call another person anywhere on the network.
If you call this “Plain Old Telephone Service,” you will have accurately explained the second acronym: POTS. Funny as it sounds, it really means this! All you need to remember is that PSTN and POTS mean exactly the same thing and are used interchangeably.

Search “10 digits cloud pbx” on google for more detail

2. PBX

PBX means Private Branch Exchange and is the “switch” in an organization’s premises that routes calls internally and externally to the PSTN/POTS.