Updated April 2026. Pricing reflects current UK business rates ex-VAT. The PSTN switch-off is confirmed for January 2027.
Why Enterprise VoIP Matters in 2026
The UK is switching off its public telephone network (PSTN) in January 2027. Every ISDN line, analogue phone line and traditional PBX will stop working.
This is not optional. Openreach is closing exchanges across the country. If your business still uses ISDN or analogue lines, you need to migrate to VoIP before the deadline.
For enterprise VoIP UK adopters with 50+ users, this is also a major opportunity. Cloud telephony costs less, scales faster and integrates with your existing tools.
Understanding Your Options
Microsoft Teams Direct Routing
If your organisation already uses Microsoft 365, Teams Direct Routing adds full phone system capabilities to Teams.
- How it works: A Session Border Controller (SBC) connects Teams to the public phone network via SIP trunks
- Licensing: Teams Phone Standard at £6.60/user/month (or included in E5)
- Best for: Microsoft 365 businesses wanting a single app for calls, meetings and chat
- Call quality: Depends on your internet connection — works best with QoS-enabled SD-WAN
Benefits for enterprise:
- No separate phone system to manage — everything in Teams
- Works from any device: desktop, mobile, browser
- Integrates with Outlook, SharePoint and Power Platform
- Call recording, auto-attendant and call queues included
- One number that follows the user across devices
Hosted VoIP / Cloud PBX
A fully managed phone system hosted in the cloud. No hardware to maintain on-site.
- How it works: Your provider hosts and manages the PBX. You connect IP phones or softphones.
- Cost: £6-15/user/month depending on features
- Best for: Businesses wanting a standalone phone system with advanced call handling
Connection Technologies offers Hypercloud, our own hosted VoIP platform built for UK businesses. Features include:
- Auto-attendant and IVR menus
- Call recording with cloud storage
- CRM integration (Salesforce, HubSpot, Zoho)
- Call analytics dashboard
- Mobile app for remote workers
- 99.99% uptime SLA
Learn more about Hypercloud hosted VoIP.
SIP Trunking
SIP trunking connects your existing PBX to the internet. It replaces ISDN lines without replacing your phone system.
- How it works: SIP channels carry voice calls over your internet connection to/from the public network
- Cost: £3-5 per channel per month, plus call charges
- Best for: Businesses with a working on-premises PBX that want to keep it
Read our dedicated cloud telephony guide for a deeper comparison.
UCaaS Platforms
Unified Communications as a Service combines voice, video, messaging, file sharing and contact centre in one platform.
- Providers: RingCentral, 8×8, Zoom Phone, Vonage, Dialpad
- Cost: £12-30/user/month depending on tier
- Best for: Large businesses wanting a fully integrated communications stack independent of Microsoft
Comparison Table
| Solution | Cost/User | Best For | Complexity |
|---|---|---|---|
| Teams Direct Routing | £6.60/mo + SIP | M365 businesses | Medium |
| Hosted VoIP (Hypercloud) | £6-15/mo | Standalone phone system | Low |
| SIP Trunking | £3-5/channel | Keep existing PBX | Low |
| UCaaS (RingCentral etc.) | £12-30/mo | All-in-one comms | Low-Medium |
Ready to Upgrade Your Phone System?
From Teams Direct Routing to our own Hypercloud platform, we manage the entire migration — number porting, training and ongoing support.
The PSTN Switch-Off: What Enterprises Must Do
Timeline
- Now: Openreach has stopped selling new ISDN/analogue lines
- September 2026: Remaining ISDN migrations must be underway
- January 2027: PSTN fully switched off — all remaining lines cease
What Stops Working
- ISDN2 and ISDN30 lines
- Analogue phone lines
- Fax machines on traditional lines
- Alarm systems and lift phones connected to PSTN
- EPOS/PDQ machines using phone line diallers
What You Need to Do
- Audit every phone line and ISDN channel your business uses
- Identify all non-voice services connected to phone lines (alarms, lifts, fax, EPOS)
- Choose your replacement solution (Teams, hosted VoIP, SIP trunking)
- Plan the migration — allow 3-6 months for enterprise-scale deployments
- Test before cutover — run new and old in parallel where possible
Don’t leave your enterprise VoIP UK migration until Q4 2026. Migration capacity is limited and providers are busy. Start your assessment now.
Enterprise Contact Centre Features
For businesses handling high call volumes, VoIP platforms offer features that traditional PBXs can’t match:
- IVR (Interactive Voice Response): Multi-level auto-attendant menus
- Call queuing: Hold music, position announcements, callback options
- Call recording: Automatic recording with cloud storage and search
- Wallboards: Real-time dashboards showing queue length, wait times, agent status
- CRM integration: Screen pops showing caller details before you answer
- Analytics: Call volume trends, peak times, abandoned call rates, agent performance
- Omnichannel: Voice, email, chat and social media in one queue
Enterprise Reliability and Redundancy
When telephony is business-critical, you need guaranteed uptime:
- 99.99% SLA: Maximum 52 minutes of downtime per year
- Geographic redundancy: Platform hosted across multiple UK data centres
- Automatic failover: If one data centre fails, calls route to another instantly
- Mobile failover: Calls forward to mobile phones if internet drops
- Disaster recovery: Pre-configured DR plans that activate automatically
Read about business continuity planning for telecoms.
Migration Roadmap: 200 Users from ISDN to Cloud
Here’s how Connection Technologies typically handles an enterprise VoIP UK migration:
| Week | Phase | Activities |
|---|---|---|
| 1-2 | Discovery | Audit existing lines, map call flows, identify requirements |
| 3-4 | Design | Solution architecture, user groupings, auto-attendant design, DR plan |
| 5-6 | Build | Platform configuration, number porting applications, handset orders |
| 7-8 | Test | UAT with pilot group (10-20 users), refine call routing, train champions |
| 9-10 | Deploy | Phased rollout in batches of 50 users, number porting, handset delivery |
| 11-12 | Optimise | Post-go-live support, user training, call flow adjustments, ISDN line cessation |
Our project management team handles every step. Your IT team stays focused on their day job while we deliver the migration.
The Connection Technologies Approach
- Platform options: We offer our own Hypercloud hosted VoIP platform plus Teams Direct Routing, SIP trunking and partner UCaaS solutions
- Vendor-neutral advice: We recommend the best solution for your needs, not the one with the highest margin
- Management portal: Enterprise clients get a dedicated portal to manage users, call routing, auto-attendants and view real-time call analytics
- Project management: Our technical team runs the entire migration — discovery, design, build, test, deploy and optimise
- Named account manager: Ongoing support, quarterly reviews and proactive recommendations
- UK-based support: No overseas call centres. Real engineers who understand your setup.
See our VoIP provider comparison for pricing details, or read about VoIP costs.
Choosing the Right Solution
Choose Teams Direct Routing If:
- Your business is heavily invested in Microsoft 365
- Users already live in Teams for messaging and meetings
- You want one app for all communications
- You have E5 licensing (Teams Phone included)
Choose Hosted VoIP / Hypercloud If:
- You want a dedicated, standalone phone system
- Advanced call handling features are important (IVR, wallboards, analytics)
- You don’t use Microsoft 365 or prefer a separate phone platform
- You want UK-based hosting with guaranteed SLAs
Choose SIP Trunking If:
- You have a modern on-premises PBX that you want to keep
- You just need to replace ISDN lines before the switch-off
- Budget is the primary concern (SIP is cheapest)
Choose UCaaS If:
- You want voice, video, messaging and contact centre in one platform
- Your business is not Microsoft-centric
- You need advanced contact centre features out of the box
Not sure which is right? Get a free assessment — our team will recommend the best option for your business.
Pricing Deep Dive
Enterprise VoIP UK pricing for a 200-user organisation:
| Solution | Per User/mo | 200 Users/mo | Annual Total |
|---|---|---|---|
| Teams Direct Routing | ~£8.50 | £1,700 | £20,400 |
| Hosted VoIP (Hypercloud) | ~£9.00 | £1,800 | £21,600 |
| SIP Trunking (60 channels) | ~£1.50* | £300* | £3,600* |
| UCaaS (RingCentral) | ~£22.00 | £4,400 | £52,800 |
*SIP trunking pricing is per channel, not per user. Assumes 60 concurrent channels for 200 users. Call charges additional. Requires existing PBX.
Compare with typical ISDN30 costs of £12-15/channel plus call charges. Cloud telephony is almost always cheaper than what it replaces.
Don’t Wait for the PSTN Switch-Off
January 2027 is closer than you think. Our team has migrated thousands of UK business lines — let us handle yours.
Frequently Asked Questions
All ISDN and analogue phone lines stop working. Businesses must migrate to VoIP, SIP trunking or a cloud phone system before January 2027. Openreach has already stopped selling new ISDN lines and is actively migrating existing customers.
Teams Direct Routing costs approximately £8.50/user/month (licensing + SIP). Hosted VoIP like Hypercloud starts at £6-9/user/month. SIP trunking is cheapest at £3-5/channel but requires an existing PBX. Volume discounts apply for 50+ users.
Yes, for most businesses. Teams with Direct Routing or Operator Connect provides call queues, auto-attendant, voicemail, call recording and mobile apps. It lacks some advanced contact centre features compared to dedicated UCaaS platforms, but for standard business telephony it is excellent.
A typical 200-user migration takes 10-12 weeks from discovery to go-live. Smaller deployments of 50 users can complete in 4-6 weeks. Our project management team handles the entire process including number porting, configuration and user training.
Hypercloud is Connection Technologies’ own hosted VoIP platform. It provides a full cloud phone system with auto-attendant, call recording, analytics, CRM integration and a mobile app. Pricing starts at £6/user/month with 99.99% uptime SLA and UK-based support.
Yes. Number porting transfers your existing phone numbers to the new platform. The process takes 5-10 working days per batch. We coordinate porting in phases to ensure no numbers are lost or unavailable during the migration.
Fax can move to cloud fax services (fax-to-email). Alarm systems and lift phones need analogue telephone adapters (ATAs) or GSM-based alternatives. Our discovery phase identifies all non-voice services and plans appropriate replacements.
Enterprise VoIP UK — Market Data and Trends 2026
Ofcom confirms the PSTN switch-off deadline of January 2027 makes enterprise VoIP UK migration mandatory for all businesses still on traditional lines. Gartner reports 62% of UK enterprises have completed their enterprise VoIP UK migration in 2026, with the remaining 38% racing to meet the deadline.
Enterprise VoIP UK key metrics for 2026:
- Forrester calculates 42% average cost savings for enterprise VoIP UK vs traditional telephony
- Enterprise VoIP UK uptime SLA: 99.99% from leading providers
- Teams Direct Routing adoption among enterprise VoIP UK deployments: 54%
- Average enterprise VoIP UK deployment for 200 users: 4-8 weeks
- Enterprise VoIP UK call quality: 4.3 MOS average (vs 3.8 PSTN)
Connection Technologies deploys enterprise VoIP UK solutions from £8.95/user/month in 2026. Get an enterprise VoIP UK quote →
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