Choosing an IP PBX is no longer just a technical decision: it directly impacts your customer experience, team productivity, and your company’s costs.
With so many IP telephony and VoIP PBX solutions on the market, it is easy to get lost among features, licences, pricing models, and commercial promises.
This comparative guide walks you through the main types of IP PBX systems, the advantages of each model, and the key criteria you should prioritise before signing any contract, with a practical focus on SMEs and mid-sized companies.
Throughout the article you will also see how a specialised partner like Inmove IT Solutions can support you in the design, deployment, and maintenance of your IP telephony solution, fully integrated with your network and IT infrastructure.
Why IP telephony is key for your business communication
Before diving into the PBX comparison, it’s worth remembering why IP telephony has become the standard over traditional telephony in many organisations.
IP telephony routes calls through the data network instead of depending on analogue or ISDN lines. This reduces costs, improves flexibility, and enables advanced features such as call queues, IVR, call recording, reporting, or CRM integration.
For a growing SME, having a well-designed IP communications solution can make the difference between a rigid phone service and a system that evolves with the business, including remote work, distributed offices, and mobile sales teams.
If you want a broader view of the benefits of IP telephony, you can go deeper in Inmove IT’s dedicated VoIP article: VoIP for SMEs: transform your business communications
VoIP PBX systems for companies: what options exist
When people talk about VoIP PBX systems for companies, they often mix very different solutions in the same bucket. However, from a technical and operational perspective it is not the same to maintain a physical device in your data centre as it is to contract a virtual PBX in the cloud or deploy a platform based on Asterisk.
Simplifying a bit, the main IP PBX options you can consider are the following:
- Physical IP PBX at your premises (on-premise).
- Virtual PBX in the cloud (hosted PBX).
- IP PBX based on open-source software (for example, Asterisk).
- Hybrid solutions combining traditional telephony and IP.
Each model combines initial investment, monthly costs, flexibility, vendor dependency, and level of technical control in a different way. Understanding these differences is key before requesting quotes or migrating from your current system.
Key criteria to compare IP PBX systems in your company
Before reviewing each alternative, it is worth defining a simple checklist to compare IP PBX systems with objective criteria and not only by price or by what your telco offers.
These are some of the most important decision drivers to keep in mind:
- Total Cost of Ownership (TCO): don’t look only at the monthly fee. Include licences, devices, migration, maintenance, training, and any penalties for commitment or upgrades.
- Scalability and number of extensions: analyse how much it will cost to go, for example, from 20 to 60 extensions. Check whether there are rigid licensing tiers or if you can grow step by step.
- Locations and remote work: if you have multiple sites, mobile sales staff, or remote workers, the solution must make remote extensions and mobility easy without complex configurations.
- Advanced features: IVR, call queues, recording, reporting, CRM integration, softphones, video calls, or even omnichannel capabilities such as chat or WhatsApp Business.
- Integration with your network and systems: the IP PBX must coexist with your corporate network, firewalls, WiFi, collaboration tools and, in many cases, with your CRM and Helpdesk solution.
- Security and compliance: check encryption options, access controls, system patching, and security best practices to avoid call fraud or attacks on your network.
- Support and maintenance: define who will handle support (telco, local partner, internal team) and what real SLA you will have for critical incidents.
- Data location and regulations: in regulated environments it is important to know where recordings and reports are stored and what guarantees the provider offers.
Having these criteria written down will allow you to compare providers with an objective matrix and avoid decisions based purely on the lowest quote.
Comparison of IP PBX types: pros and cons
With the criteria clear, we can analyse the main alternatives to deploy an IP PBX in your company, with their advantages, limitations, and typical fit depending on size and technological maturity.
Physical IP PBX in your office (on-premise)
The physical IP PBX is a device installed in your data centre or comms room. It integrates with your data network and usually with SIP trunks or lines provided by your carrier.
Its main advantages and drawbacks are:
- Advantages:
- Full control over hardware and configuration.
- Possibility of very specific integrations with internal applications or legacy systems.
- Interesting option when regulations require voice to remain on your own premises.
- Drawbacks:
- Higher up-front investment in hardware, licences, and deployment.
- Dependency on local infrastructure: power issues, cooling problems, or Internet outages can affect the service.
- More limited scalability, often linked to physical expansions of the PBX.
This model usually fits organisations with a consolidated in-house data centre, internal IT staff, and special control or integration requirements.
Virtual PBX in the cloud (hosted PBX)
The virtual PBX is a service hosted in the provider’s cloud or by a specialised vendor. You only need IP phones or softphones and good Internet connectivity.
It is one of the most common options for SMEs and growing companies, especially when combined with well-designed communications and networking projects.
- Advantages:
- No upfront investment in “iron”: it typically follows a per-user or per-channel subscription model.
- Very high scalability: adding extensions or sites usually only involves licence changes.
- Excellent fit for remote work, distributed offices, and mobile sales teams.
- Updates, security, and maintenance are delegated to the provider.
- Drawbacks:
- Greater dependence on Internet connectivity and on the VoIP provider’s SLA.
- Less control over very specific configurations or custom developments.
- Possible complexity in advanced integrations beyond the standard catalogue.
For many SMEs, the virtual PBX is the most balanced option in terms of cost, flexibility, and time-to-deploy. If you are considering this kind of model, you can review the services of: IP telephony and VoIP PBX solutions for businesses by Inmove IT Solutions
IP PBX based on Asterisk and open-source solutions
Solutions based on Asterisk and other open-source stacks allow you to design very flexible IP PBX systems, either on your own servers or in cloud environments.
This approach is particularly interesting when you need a PBX deeply integrated with your systems (CRM, ERP, Helpdesk) and want to keep a balance between control, customisation, and cost.
- Advantages:
- Very high level of customisation for call flows, queues, schedules, and business logic.
- Ability to deploy on your own cloud infrastructure or in a trusted data centre.
- Very competitive licensing model as it is based on open-source software.
- Drawbacks:
- Requires a partner with real-world Asterisk experience for design, hardening, and support.
- Greater responsibility for security updates and vulnerability management.
- Without proper design it can become a complex system to maintain in the long term.
In this area, Inmove IT Solutions works on projects like: VoIP PBX with Asterisk tailored to each company’s needs
Hybrid solutions: gradual transition from traditional telephony
Hybrid PBX systems combine part of the classic infrastructure (ISDN, analogue) with IP and VoIP capabilities. They are common in organisations migrating in phases that cannot transform all telephony at once.
They are an attractive transitional option when you have a large base of analogue phones or ongoing contracts with operators and want to move towards a 100% IP model gradually.
- Advantages:
- Leverage existing investments in equipment, cabling, and line contracts.
- Reduce migration risk by keeping traditional telephony in parallel.
- Enable IP features without a radical infrastructure change.
- Drawbacks:
- Two worlds coexist (analogue and IP), which can increase complexity.
- In the medium term, it can be more expensive than going straight to a well-planned IP architecture.
If you are in a transition phase, it is worth looking at options such as: cloud and on-prem PBX solutions integrated with your existing infrastructure
Practical steps to choose the best IP PBX for your company
Beyond the specific technology, your decision must be based on a clear understanding of your actual situation. These steps will help you structure the selection process for an IP PBX in your organisation.
Here is a simple roadmap you can follow internally or together with your technology partner.
- Analyse your current situation
- Volume of inbound and outbound calls.
- Number of users, sites, and remote work scenarios.
- Limitations of your current system in terms of cost, features, and support.
- Define business and IT objectives
- Do you want to reduce costs, improve customer service, enable remote work, or unify sites?
- Prioritise three or four objectives and rank them by business impact.
- Classify functional requirements
- Must-haves: for example, integration with your CRM or call queues per department.
- Nice-to-haves: call recording, advanced reporting, or integration with support tools.
- Optional: integrated video calls, full omnichannel, very specific functions.
- Assess the state of your network and connectivity
- Review the quality of your LAN, WiFi, and Internet connections.
- An IP PBX running over an unstable network will cause a poor experience, regardless of the platform.
- At this point, you may need a professional business communications and networking project to guarantee voice traffic quality.
- Request comparable proposals
- Ask several providers for quotes based on the same scenario (users, sites, features, contract length).
- Demand detailed information on licences, migration costs, support, and lock-ins.
- Evaluate guidance and support
- It is not just about a platform: you need a partner who understands your IT infrastructure and can support you as the solution evolves.
- Check whether they can also help you in areas such as maintenance, monitoring, and security.
Security and service quality: the less visible side of the IP PBX
A common mistake is to compare IP PBX systems purely by visible features and price. However, VoIP security and Quality of Service (QoS) are just as important.
Telephony fraud or a PBX saturated at peak times can generate costs far higher than any savings from a cheaper monthly fee.
Some minimum best practices you should demand or implement include the following:
- VoIP security and hardening:
- Use of encryption for signalling and media whenever possible.
- Strong password policies for extensions and admin panels.
- Restricted access by IP, allowlists, and segmentation of the voice network.
- Perimeter protection and network segmentation:
- Firewall rules properly tuned for SIP/VoIP traffic.
- Dedicated voice VLANs to avoid interference with other services.
- Continuous monitoring of attack attempts and anomalous usage.
- 24/7 monitoring and proactive alerts:
- Monitoring of PBX status, trunks, and call quality.
- Automatic alerts for outages, high latency, or suspicious call patterns.
A good practice is to combine your PBX with IT maintenance and 24/7 monitoring services, so telephony is not isolated from your overall security and continuity strategy.
As an additional reference, you can consult the cybersecurity resources for companies published by INCIBE (Spanish National Cybersecurity Institute): INCIBE cybersecurity resources for businesses
How Inmove IT Solutions helps you define your IP telephony strategy
Choosing an IP PBX should not be an isolated project, but part of a broader communications and technology infrastructure strategy.
At Inmove IT Solutions we start by analysing your network, your ways of working, and the applications you already use, in order to propose the right combination of PBX, connectivity, security, and maintenance.
- Design and deployment of IP telephony and VoIP PBX projects for businesses, whether physical, virtual, or hybrid.
- Implementation of solutions based on Asterisk and open-source software when advanced integrations are required.
- Integration of the PBX with CRM, support tools, productivity suites, and cloud services.
- IT maintenance and support services to guarantee the continuity of your communications system.
The goal is not just to swap one PBX for another, but to improve how your company communicates with customers, suppliers, and internal teams, aligning your voice solution with your digital strategy.
Frequently asked questions about choosing an IP PBX
These are some of the most common questions that arise when comparing IP PBX options in SME and mid-market environments.
What is the difference between a physical IP PBX and a virtual PBX?
A physical IP PBX is a device installed in your own premises, whereas a virtual PBX is hosted in the provider’s cloud. The physical PBX requires higher up-front investment and internal management but offers more control. The virtual PBX usually follows a pay-per-use model, is easier to scale, and delegates maintenance to the provider, at the cost of more dependency on connectivity and the service SLA.
What bandwidth do I need to deploy IP telephony?
It depends on the number of simultaneous calls and the codec used, but as a rough guide you can calculate between 80 and 100 kbps symmetrical per call for acceptable voice quality. Besides bandwidth, it is crucial to ensure proper network configuration (QoS, voice VLAN, low and stable latency) to guarantee service quality.
Is IP telephony secure for businesses?
Yes, as long as it is configured and managed correctly. It is important to apply encryption whenever possible, harden access credentials, limit connections by IP, place the PBX behind a firewall, and keep the system up to date. It is also advisable to monitor usage and call patterns to detect possible fraud or attack attempts.
Which option is better for a growing SME: physical or virtual PBX?
For most SMEs, a cloud-based virtual PBX or a managed VoIP PBX solution provided by a partner is usually the most flexible and cost-effective option. It lets you start with a small number of extensions, grow without major hardware investments, and enable remote work and branch offices. Physical PBX systems are typically reserved for environments with special requirements around integration, regulation, or internal control.
Can I integrate the IP PBX with my CRM and other tools?
Yes. Many IP telephony platforms and VoIP PBX solutions provide connectors for CRM, ticketing tools, or productivity suites. This allows you to log calls automatically, dial with a single click from the CRM, and access advanced reports. In Asterisk-based solutions, these integrations can be highly customised, as long as you work with a partner experienced in this type of project.
