Two Approaches to Business Phone Systems

When choosing a business phone system in 2026, you have two main options: hosted VoIP (cloud-based) or on-premise PBX (hardware in your office). Both use VoIP technology, but they differ significantly in how they're deployed, managed, and paid for.

Let's break down the differences so you can make the right choice for your Northern Ireland business.

What is Hosted VoIP?

Hosted VoIP (also called cloud PBX or UCaaS) is a phone system that runs entirely in the cloud. Your provider hosts and maintains all the infrastructure in their data centres. You just need IP handsets or softphones and an internet connection.

• No hardware to buy or maintain on your premises
• Managed entirely by your provider
• Pay a monthly per-user fee
• Access from anywhere — office, home, mobile
• Automatic updates and new features

What is On-Premise PBX?

An on-premise PBX is a physical phone system installed in your office. You own the hardware, and it connects to the phone network via SIP trunks. Your IT team (or a managed service provider) is responsible for maintenance and updates.

• Hardware installed on your premises
• You own and control the system
• Higher upfront cost, lower ongoing costs at scale
• Requires IT expertise to manage
• Full customisation and control

Cost Comparison

Hosted VoIP Costs

• Setup: Free to £500
• Monthly: £8-20 per user (calls usually included)
• Handsets: £50-200 per handset (or use softphones for free)
• Maintenance: £0 (included in monthly fee)
• 5-year cost for 20 users: £12,000-24,000

On-Premise PBX Costs

• PBX hardware: £3,000-15,000
• Installation: £500-2,000
• SIP trunks: £50-100/month (for channels)
• Handsets: £50-200 per handset
• Maintenance contract: £500-2,000/year
• 5-year cost for 20 users: £15,000-35,000

For a detailed breakdown, see our guide on business phone system costs.

Feature Comparison

Both systems offer similar core features, but there are differences in how they're delivered:

• Mobile apps: Standard with hosted VoIP. Possible but often limited with on-premise
• Call recording: Included with most hosted plans. May require additional licensing on-premise
• Teams integration: Easier with hosted VoIP. Possible but more complex on-premise
• CRM integration: Available on both, but hosted platforms often have more pre-built integrations
• Auto-attendant: Standard on both
• Call analytics: Real-time dashboards standard with hosted. May need add-ons for on-premise
• Customisation: On-premise offers deeper customisation for complex requirements

Reliability and Uptime

This is where the debate gets interesting:

• Hosted VoIP: Relies on your internet connection AND the provider's cloud infrastructure. Good providers offer 99.99% uptime with geographic redundancy. If your internet goes down, calls can failover to mobiles
• On-premise PBX: Relies on your internet connection (for SIP trunks) AND your local hardware. If the PBX fails, you need an engineer. But internal calls between extensions work even without internet

In practice, hosted VoIP with a backup internet connection provides excellent reliability for most businesses.

Management and Maintenance

• Hosted VoIP: Your provider handles everything — updates, security patches, hardware maintenance. You manage users and settings through a simple web portal
• On-premise PBX: You're responsible for updates, security, backups, and hardware maintenance. Most businesses need a maintenance contract or in-house IT staff

Scalability

• Hosted VoIP: Add or remove users in minutes. Scale from 2 to 2,000 users without changing platforms
• On-premise PBX: Limited by hardware capacity. Scaling up may require new hardware purchases and engineer visits

Remote and Hybrid Working

This is where hosted VoIP has a clear advantage. Remote workers can use the same phone system from anywhere — home, coffee shop, or client site — with full functionality through mobile and desktop apps.

On-premise PBX systems can support remote workers, but it typically requires VPN connections and more complex configuration.

Which Should You Choose?

Choose Hosted VoIP If:

• You're a small or medium business (2-200 users)
• You don't have dedicated IT staff
• You want predictable monthly costs with no upfront investment
• Your team works remotely or across multiple locations
• You want the latest features without managing updates

Choose On-Premise PBX If:

• You're a large enterprise with 200+ users
• You have specific compliance requirements that mandate on-site data
• You have IT staff to manage and maintain the system
• You need deep customisation that cloud platforms can't provide
• You prefer capital expenditure over operational expenditure