Cloud-based SaaS telephony or your own IP PBX on Asterisk / FreePBX: what to choose for your business

Why choosing the right telephony solution has become critical for businesses

Just ten years ago, an office PBX was simply «telephone equipment in the server room». Today, corporate telephony for business is part of a company’s operational architecture: it integrates with CRM systems, feeds data into analytics, plays a role in sales automation, influences support service SLAs, and serves as a source of evidence in disputed situations.

This means that the choice between SaaS and an in-house IP PBX affects not only the monthly bill, but also control over and access to call recordings, the flexibility of routing logic and IVR scripts, the integration of IP telephony with CRM and internal systems, the level of vendor dependency, and the system’s behaviour during incidents.

This is precisely why a platform should be chosen not on the basis of the subscription price, but on the basis of its alignment with the business scenario and the actual total cost of ownership over a 2-3-year horizon.

What is SaaS telephony and how does it work?

SaaS telephony (Software as a Service) is a model in which the provider deploys the entire telephony infrastructure on its own servers and provides access to it via a subscription. The customer does not purchase or maintain any server hardware — they connect via the internet and manage the system through a web interface or mobile app. In effect, this is Internet telephony in its purest form: Internet telephony where the entire stack is hosted by the provider.

In the context of telephony, a SaaS solution is often referred to by various names: cloud PBX, virtual PBX, VATS, cloud IP telephony, cloud SaaS telephony. All these terms describe a single model: the system logic, SIP server, call recording storage, and routing rules — all of this is located on the provider’s side. What is SaaS in this context? It is a subscription-based, multi-functional telephone system where the provider is responsible for the infrastructure, and the customer is responsible only for usage.

What is included in a typical SaaS package:

• Subscription-based solutions usually provide users with a user-friendly web dashboard from which they can directly manage the system’s features;
• Basic settings are available in all packages — number allocation, user management, call history, basic IVR menu options, etc.;
• Depending on the tariff plan, additional features may vary or be subject to extra charges — such as the number of employees, numbers, lines, etc.

What are Asterisk and FreePBX?

In practical terms, an IP-PBX is a software-based telephone system that is deployed on a dedicated server or VPS and is managed entirely by the company or its contractor.

Asterisk-based IP telephony forms the foundation upon which the telephony logic is built: processing SIP calls using the SIP protocol, routing, connecting SIP trunks and SIP lines, executing dial plans, call recording, and integration via AGI/AMI/ARI. Asterisk is a platform that needs to be deployed, secured, updated and maintained. Maintaining and configuring Asterisk FreePBX require appropriate technical expertise.

FreePBX is a graphical web interface built on top of the Asterisk IP-PBX, which significantly simplifies administration. A FreePBX-based PBX system allows you to configure extension numbers, trunks, queues, IVR and routing rules via the interface, rather than by manually editing configuration files. FreePBX IP telephony is the most common way of deploying Asterisk for business.

When selecting a contractor and evaluating proposals, it is important to understand the difference: Asterisk is the engine, whilst FreePBX is the GUI interface for managing Asterisk. IP-PBX is a general term for a class of solutions that includes Asterisk, FreePBX, and a number of commercial platforms. In everyday conversation, «Asterisk», «FreePBX» and «IP-АТС» are often used as synonyms, but technically they represent different layers of the same system.

The key difference between SaaS and an on-premises IP PBX: the ownership and management model

The most important difference between SaaS and an on-premises IP-PBX lies not in the interface or the list of features, but in who is responsible for the infrastructure and where control lies.

In the SaaS model

• The system logic, data and settings are hosted on the provider’s servers.
• Updates, backups and monitoring are the provider’s responsibility.
• Call recordings are stored in accordance with the provider’s policies.
• Customisation is limited to what the platform allows.
• If terms and conditions change or the service is discontinued, migration is entirely your responsibility.

With the Asterisk / FreePBX model

• All logic, configurations, data and records are held by you or on your server.
• Updates, security and backups are your responsibility or that of your contractor.
• Any customisation is technically possible: from non-standard IVR to your own AGI scripts.
• You are not dependent on a third-party supplier’s pricing policy or roadmap.
• But freedom goes hand in hand with responsibility for stability and security.

This is precisely where most companies go wrong: they judge their options solely on the basis of the monthly cost, without taking into account the costs of support, administration, incidents and potential migration.

A comparison of SaaS telephony and Asterisk/FreePBX based on key criteria

Let’s take a look at the most important criteria that actually influence the choice of a particular office telephony system.

Speed of deployment

SaaS almost always has the edge right from the start. A turnkey cloud-based telephony solution can be set up in a matter of hours: the provider grants access to the control panel, numbers are configured, SIP clients or online telephony software are installed on the device — and the system is ready to go. No server hardware, no lengthy infrastructure approvals.

Launching Asterisk / FreePBX takes considerably longer. Deploying IP telephony involves selecting and preparing a server or VPS, installing and performing basic configuration of Asterisk, configuring Asterisk FreePBX, configuring SIP trunks and SIP lines, setting up monitoring, and conducting security checks. The speed of deployment depends on the complexity of the technical requirements and the expertise of the contractor; the core functionality of the PBX required for operation can be set up within a single day.

Flexibility and customisation

This is one of the strongest arguments in favour of Asterisk / FreePBX. If a business has non-standard logic — such as automated outbound calls based on CRM data, complex IVRs with branching logic, IVR systems tailored to specific scenarios, or routing based on region, time of day or customer status — SaaS platforms often do not allow this to be implemented, or only do so with limitations.

AGI (Asterisk Gateway Interface) and AMI (Asterisk Manager Interface) make it possible to build virtually any logic: from integration with your own ERP to a conference call system with non-standard rules for connecting participants. In SaaS, customisation is always limited by the platform’s framework — and if your scenario goes beyond these limits, the choice is clear. But it is important to understand: any deep customisation on Asterisk is an engineering project, not a configuration via the interface.

Control over data and the system

In SaaS, a significant degree of control lies with the provider. Call recordings, call logs, routing scenarios, system access and update policies — all of this depends on the provider. The company has access to data within the limits set by the platform: downloads, retention periods, format — all according to the provider’s rules.

An in-house IP-PBX offers complete control. Business IP telephony with call recording on an in-house server means that the client independently determines where data is stored, for how long, and who has access to it and under what conditions. This is critical for financial companies, healthcare organisations, law firms — any business where there are industry standards or internal security policies regarding the storage of calls.

Implementation costs and total cost of ownership

The most common mistake is to reduce the comparison to a monthly SaaS subscription versus one-off costs for servers and configuration. The reality is more complex, and it needs to be assessed in terms of the total cost of ownership (TCO) over a 2-3-year period.

With SaaS, the visible cost is the subscription fee. This is convenient at the outset: there are no costs for equipment, telephone installation or configuration. But as the team grows, the cost rises proportionally: more users, more channels, additional modules. With 20-30 agents, the monthly subscription can exceed the cost of an in-house PBX within 6-12 months. Plus: the cost of integrations with PBX telephony systems, non-standard configurations and support is often charged outside the basic tariff.

In the Asterisk / FreePBX model, the initial costs are higher: a server or VPS, time spent deploying IP telephony, hiring a contractor to configure the telephony system and initial Asterisk maintenance. However, in the long run, this model is often more cost-effective: the cost is not tied to the number of users, and support is a fixed expense rather than a constantly rising bill. Controlling costs at scale is one of the main advantages of having your own PBX.

Don’t assess «how much it costs now», but rather «how much it will cost in two years’ time when the team has doubled in size». Only then does TCO become a practical tool for decision-making.

Scalability

SaaS is ideal where scaling is standard: new staff, new numbers, new offices — everything can be set up via the control panel without any technical work. For standard scenarios, this is a significant advantage, particularly for businesses that are growing rapidly without their operations becoming overly complex.

Asterisk / FreePBX shines when scaling is accompanied by increasing complexity: new custom scenarios, deeper integrations, advanced IP telephony organisation in an office with multiple network segments, and reliable communication between company branches via proprietary infrastructure. In such cases, a SaaS platform may reach the limits of its capabilities precisely when the business requires the greatest flexibility.

Reliability and fault tolerance

It is important not to oversimplify matters here: SaaS is not always automatically more reliable, and an in-house PBX is not always riskier. The level of fault tolerance in both models is determined by the quality of implementation, not by the model itself.

With SaaS, the customer relies on the provider’s architecture: server redundancy, geographical redundancy, monitoring and SLAs — the provider is responsible for all of this. If the provider has built the infrastructure well, this is a real advantage. If not, you will find out during an incident.

In an on-premises PBX, the level of fault tolerance is determined by what your team or contractor has done: is there a backup SIP trunk, is the fallback route to mobile configured, is there a backup internet connection, and are monitoring and configuration backups working? Without these, even the best-configured on-premises PBX is vulnerable. With these measures in place, the reliability level can exceed that of most SaaS solutions. Stable connectivity in any model is the result of deliberate architectural decisions, not an automatic feature of the platform.

Security

Both models carry risks, but of a different nature, so they should not be conflated.

In SaaS, security depends on the provider’s maturity: whether TLS encryption is used for signalling and SRTP for media streams, how call recordings are stored and protected, what the policy is regarding access to customer data, and how the provider responds to incidents. The company delegates security to the provider and has limited control over these parameters.

In Asterisk / FreePBX, the risks are more manageable, but only provided a competent approach is taken. Without it, your own PBX becomes an open target. Standard attack vectors include: an open SIP port with no restrictions, weak passwords on internal extensions and trunks, an unprotected FreePBX web interface, and open AMI ports. And as a result — SIP fraud: unauthorized calls to premium-rate numbers, which can cost thousands of dollars in a matter of hours.

Proper protection of your own PBX includes: fail2ban to block brute-force attacks, ACLs on SIP connections, TLS for signalling, SRTP for media streaming, a VPN for remote agents and external Asterisk IP telephony connections, network segmentation, closed AMI ports, secure access to the FreePBX web interface, and regular updates to the kernel and modules.

A well-secured in-house PBX provides greater control over who has access to data and how, which is critical for regulated industries. However, achieving this level of security is impossible without an experienced administrator.

Integration with CRM and other systems

SaaS solutions often come with ready-made, «out-of-the-box» integrations with popular CRMs such as KeepinCRM, HubSpot CRM, Salesforce and HubSpot. For small and medium-sized businesses, integrating IP telephony with a CRM in this way offers a significant advantage: setup takes hours rather than weeks and does not require the involvement of a developer.

In Asterisk / FreePBX, integrations with PBX systems can be almost any type via AMI, ARI or AGI. However, each of these typically constitutes a separate engineering project. As this is a fairly common solution, many platforms already have ready-made integrations with Asterisk of their own. If you need deep two-way integration with a non-standard or proprietary system, specific data exchange with an ERP, or non-standard call event processing logic — Asterisk offers far more freedom than any SaaS platform. However, one must realistically assess the cost of developing and maintaining such integrations — it is always higher than connecting a ready-made module.

Vendor lock-in

This is one of the criteria most often overlooked during the selection process — and one that people most often come to regret later on.

In the SaaS model, a business gradually builds up a dependency on a specific platform: IVR scripts, CRM integrations, team training, API connections to internal systems — all of this is tied to a single provider. If the provider changes prices, discontinues features or exits the market, migration is painful and expensive. Two years of active use of a SaaS platform can turn theoretical freedom of choice into a practical impossibility of change without significant expense.

Asterisk / FreePBX is independent in this sense. Your configurations, dial plans, routing logic, call recordings and all documentation — are yours. You can change providers, move the system to another server, or adapt it to new requirements without having to negotiate with the supplier. Provided the system is well documented and maintained without being tied to a single integrator, the level of independence is maximum. This is particularly important for businesses with a planning horizon of 3+ years and a reluctance to depend on someone else’s roadmap.

When is SaaS telephony the logical choice?

• For small or medium-sized businesses without their own IT team or with minimal IT resources.
• If you need a quick setup — from a few hours to a day.
• For standard tasks: calls, IVR, queues, call recording, and basic analytics.
• There is a need for ready-made, out-of-the-box CRM integrations.
• The team works remotely, either partially or fully, so mobility and digital telephony not tied to the office are required.
• A planning horizon of up to 1 year or a business in the active development stage.

When is it more logical to build a system on Asterisk / FreePBX?

• In call centres with complex routing logic and custom scenarios, including outbound dialling campaigns.
• There are requirements regarding data control: records, logs and access must be managed by a single person.
• There is a need for specific integrations with internal systems that SaaS platforms do not support, or for organising IP telephony in an office with a complex topology.
• For large or rapidly growing teams, where the total cost of ownership of SaaS becomes unjustified.
• There is a competent IT team or a reliable contractor to maintain and secure the system.
• There are requirements relating to industry standards or internal security policies.

Common mistakes when selecting and implementing a telephony system

Most problems arise as early as the stage of selecting or deploying a corporate telephony architecture. Here are the most common ones and their real-world consequences:

1. Comparing only the upfront cost without considering the total cost of ownership (TCO). SaaS appears cheaper because there are no costs for servers or configuration. However, with 20-30 users, the monthly subscription fee can exceed the cost of an in-house PBX within 6-12 months. Calculate the TCO over 2-3 years — taking into account scalability, support and the cost of integrations.
2. Deploying Asterisk without an experienced administrator. Asterisk «out of the box» is unsecured. Open SIP ports, default passwords, and the absence of fail2ban are a direct route to fraud via internet telephony. Costs can run into thousands of dollars in a matter of hours. The cost of a competent administrator is always less than the cost of an incident.
3. Ignoring the quality of the internet connection. The most common technical error, regardless of the model. VoIP and office IP telephony are critically dependent on the stability of the connection. A ping above 80 ms, packet loss exceeding 1%, and the absence of QoS — and call quality deteriorates regardless of whether it is SaaS or Asterisk.
4. Underestimating the cost of Asterisk support. When deciding to opt for free open-source software, it is important to realise that the true cost includes the administrator’s time spent on support and updates, debugging after every FreePBX patch, and integration support. Without taking these costs into account, the «free» solution ends up being more expensive than a subscription.
5. Lack of a backup plan. Neither SaaS nor an in-house PBX is automatically protected against failures. A backup SIP trunk, a fallback route to a mobile number, and a backup internet connection are basic requirements for reliable business communications, not optional extras.
6. Lock-in to a single provider. Two years on a SaaS platform — and suddenly it turns out that all integrations, workflows and team training are tied to a specific provider. Migration costs more than any expected savings. So plan for independence in advance.

A practical checklist for choosing a telephony solution

Before making a decision, please answer these questions honestly. They will help you determine which solution is best suited to your situation.

About scale and team

• ☐ How many users do you currently have, and how many are expected in 1-2 years?
• ☐ Do you have a dedicated IT team or a competent systems administrator?
• ☐ Do you have experience working with Asterisk / FreePBX or a reliable contractor with a proven track record?

About system requirements

• ☐ Do you need non-standard routing logic or a custom IVR?
• ☐ Which CRMs and internal systems need to be integrated? Does the SaaS provider offer ready-made integrations?
• ☐ Where should call recordings be stored — in the provider’s cloud or on your own servers?
• ☐ What are the security and compliance requirements in your industry?

On budget and time horizon

• ☐ What is the initial budget, and what is the acceptable monthly cost in two years’ time as the team grows?
• ☐ Has the TCO been calculated for both models over a 2-3-year time horizon — including support and incidents?
• ☐ What is the cost of telephony downtime to the business, and is a contingency plan in place?

On dependency and flexibility

• ☐ How critical is vendor independence and full control over data?
• ☐ Do you plan to significantly change the logic, scale or set of integrations in the next two years?
• ☐ Is there a contingency plan in place in the event of a failure of the primary channel or a PBX outage?
• ☐ Is the current telephony configuration documented in such a way that it can be recreated or migrated?

Let’s be clear. SaaS telephony and Asterisk/FreePBX are not competing in a «which is better» contest. They are different tools for different tasks, and the right choice depends on the specific context, not on general rankings.

SaaS is a strong choice where speed, simplicity and minimal technical responsibility are important. Cloud-based «subscription» telephony is a convenient model for businesses without their own IT team, for standard scenarios and without the need to delve deeply into the infrastructure.

Asterisk / FreePBX is best suited where control, flexibility, non-standard logic and long-term manageability are required. An in-house Asterisk IP-PBX is the solution for contact centres, companies with heightened security requirements, large teams or businesses that want complete control over their telephony infrastructure.

The key is to start not by choosing a platform, but by understanding your own business scenarios, security requirements, scalability, and actual TCO.

At Maxnet, you can obtain a virtual PBX based on Asterisk/FreePBX as a ready-to-use cloud service. This combines the advantages of an open-source solution — flexible configuration, extensive functionality, integrations and the ability to scale to meet business needs — with the convenience of the SaaS model, where infrastructure, technical configuration and professional support are provided by our engineers.

This approach allows you to utilise the capabilities of a full-featured IP PBX without having to manage servers, updates or complex telephony logic yourself. If you need a telephony solution that doesn’t restrict your business to standard service frameworks, please contact us — we’ll help you select and configure a solution tailored to your requirements.