With the UK’s PSTN switch-off looming, more and more businesses are migrating to VoIP systems, and while VoIP is flexible, scalable, and cost-effective, it’s only as good as the internet connection that powers it.
So, do you need a leased line for VoIP for UK businesses? Or will business broadband do the job?
Join us as we explore the pros and cons of different internet connections for VoIP, what makes a VoIP-ready business internet service, and how to ensure crystal-clear calls every time.
What Is VoIP and Why Is It Replacing Traditional Phones?
VoIP enables voice calls to be transmitted over the Internet instead of copper phone lines… Some of the top benefits include:
- Lower costs compared to ISDN/PSTN lines
- Greater flexibility (remote working, call forwarding, mobile apps)
- Scalability (add/remove lines easily)
- Integrates with CRM and UC tools
With BT Openreach retiring the public switched telephone network (PSTN) by the end of 2025, all UK businesses must switch to digital phone services like VoIP!
Internet Requirements for VoIP
VoIP doesn’t require massive bandwidth, but it does demand:
- Consistent speeds
- Low latency (ideally < 50ms)
- Minimal jitter (ideally < 30ms)
- Stable upload and download rates
Here’s how different internet types compare:
Connection Type | Upload Speed | Contention | Latency | VoIP Ready? | Notes |
Standard Broadband (FTTC) | 10-20Mbps | Shared | Medium | ❌ | OK for small teams, but inconsistent |
FTTP (Fibre to the Premises) | 100-300Mbps | Shared | Low | ✅ (small teams) | Can handle VoIP for <10 users |
4G/5G Mobile Broadband | 10-300Mbps | Shared | High | ❌ | Not stable enough for VoIP |
Leased Line (Dedicated Fibre) | 100Mbps-10Gbps | 1:1 | Very Low | ✅ (all sizes) | Designed for consistent voice traffic |
Why a Leased Line Is Ideal for VoIP
A leased line is a dedicated internet connection with symmetrical speeds and no contention, it guarantees consistent performance, making it ideal for:
- Businesses with 10+ phone users
- Call centres or customer support teams
- Remote or hybrid workforces using softphones
- Companies relying on voice quality for sales or service delivery
Benefits of Leased Lines for VoIP:
- Symmetrical upload/download speeds: Crucial for clear two-way calls
- 1:1 contention: No risk of slowdowns due to shared usage
- Low jitter and latency: Prevents echo, delay, and call drops
- High uptime with SLAs: Fix times within 4-5 hours guaranteed
How Many VoIP Users Can Your Bandwidth Handle?
As a general guide:
- Each VoIP call uses ~100kbps in both directions (upload + download)
- A 100Mbps leased line can support 500+ simultaneous VoIP calls
Users | Minimum Recommended Connection |
1-5 | FTTP or Business Broadband |
6-20 | FTTP (uncontended) or Leased Line |
20+ | Leased Line (100Mbps+) |
100+ (Call Centre) | 1Gbps Leased Line or higher |
VoIP Features That Need a Stable Connection
- Call recording
- Auto-attendant menus
- Call forwarding
- Voicemail-to-email
- Video calls via UCaaS systems (e.g. Microsoft Teams, Zoom Phone)
- CRM integration (live call syncing)
Best UK Leased Line Providers for VoIP
| Provider | Leased Line Plans | VoIP Features Supported | From: |
| 100Mbps – 10Gbps | VoIP, SIP, Hosted Voice | £399 |
| 100Mbps – 10Gbps | SIP Trunks, UCaaS | £400 |
| 100Mbps – 10Gbps | Hosted VoIP & PBX | £450 |
| 100Mbps – 1Gbps | SIP, Hosted VoIP | £300 |
| 100Mbps – 1Gbps | VoIP-ready broadband | £375 |
What If You Can’t Get a Leased Line?
If you’re in a remote area or a leased line isn’t feasible:
- Choose a business-grade FTTP service with static IPs and low contention
- Use a QoS-enabled router to prioritise VoIP traffic
- Consider SD-WAN to balance voice and data loads
Final Thoughts About Leased Line For VoIP Systems
If your business switches to VoIP in 2025, your internet must be ready for the change, and for some small teams, FTTP may be sufficient. But a leased line for a VoIP UK setup is the safest long-term investment for growing SMEs or businesses that rely on voice quality.