Key Takeaways
- NEC exited the unified communications market in 2024. Manufacturer support is no longer guaranteed and spare parts are becoming scarce.
- ISDN lines connected to NEC systems will be permanently switched off in January 2027.
- NEC SL2100, SV8100 and SV9100 systems can support SIP trunking, but capability varies by version, cards and licensing.
- NEC SL1100 systems are older, SIP support is more limited and full replacement is often the more practical option.
- Before making any changes, the system version, cards, licences and handset models need to be checked. Two NEC systems can look similar from the outside but be very different internally.
NEC Phone Systems and the ISDN Switch-Off
NEC business phone systems have been a reliable presence in Northern Ireland for many years. The SL1100, SL2100, SV8100 and SV9100 platforms have served offices, hotels, healthcare premises and multi-site businesses well. Many of these systems are still in daily use and performing fine.
The problem is not the hardware itself. The problem is that two things are happening at the same time.
First, NEC sold its telephone equipment division in 2024 and exited the unified communications market. This means no new systems, reducing spare parts availability, and no guarantee of ongoing manufacturer support. Second, BT Openreach is switching off the UK's PSTN and ISDN network in January 2027. Any NEC system connected via ISDN lines will lose its ability to make or receive calls via those lines on that date.
If you have an NEC system in your Northern Ireland business, you need to understand your options and start planning now.
Important note before you start: Before making changes to any NEC system, the system version, fitted cards, licence files and handset models need to be checked. Two NEC systems can look similar from the outside but be very different internally. This applies to SIP capability, channel capacity and handset compatibility.
NEC System Models in Northern Ireland
NEC SL1100
A smaller PBX aimed at businesses with up to 48 extensions. Common in small offices, retail premises and professional services across NI. The SL1100 has limited SIP trunk support compared to the SL2100 and its successors. In many cases, the cost and complexity of retrofitting SIP capability makes full replacement with hosted VoIP more practical.
- Older platform: typically installed 10 or more years ago
- Limited SIP trunk capacity without additional hardware
- Analogue and digital handsets only: no SIP handsets native to this platform
- End-of-life hardware: replacement parts are increasingly difficult to source
Likely migration path: Full replacement with hosted VoIP.
NEC SL2100
The most recent smaller NEC platform. More capable than the SL1100 and with better SIP support. Still widely deployed across Northern Ireland businesses.
- Supports SIP trunking via the web maintenance console
- SIP channel capacity depends on the IP4WW-VOIPDB daughter board and current licensing
- NEC DT3 and DT4 series digital handsets: proprietary, cannot be reused on other platforms
- Some NEC SIP handsets (DT920 SIP series) may be compatible with third-party VoIP platforms, but this requires testing
- DECT cordless handsets (if fitted) are proprietary to the SL2100 platform
Migration path: SIP trunking (keep the system) or full hosted VoIP replacement. An assessment of the fitted cards, version and licensing is needed first.
NEC SV8100
A mid-to-large business platform that can handle hundreds of extensions across multiple sites. Still in use in hotels, large offices and multi-location businesses across Northern Ireland. More capable SIP support than the SL series.
- Strong SIP trunk support when properly licenced
- Supports IP handsets natively
- Licencing is complex: UNIVERGE licensing must be reviewed before SIP migration
- Some SV8100 handsets may be compatible with standards-based SIP platforms, but this is not guaranteed and requires testing
- Hardware support is now only available through third-party channels
Migration path: SIP trunking is viable if licencing supports it. Full hosted VoIP replacement avoids ongoing hardware dependency.
NEC SV9100
The most recent and capable NEC platform. Found in larger businesses, hotels and multi-site operations across NI. Good SIP support, but the same hardware support issues apply.
- Strong SIP trunk support when correctly configured and licenced
- Supports NEC SIP handsets (DT900 series)
- Some DT900 series SIP handsets may work on third-party platforms, subject to testing
- UNIVERGE licensing model: review licences before migrating to ensure channel capacity is adequate
- Hardware support through third-party channels only following NEC's market exit
Migration path: SIP trunking is viable for the medium term. Full hosted VoIP replacement removes ongoing hardware dependency.
Option 1: SIP Trunking (Keep the NEC System)
For businesses with NEC SL2100, SV8100 or SV9100 systems, SIP trunking replaces the ISDN lines while keeping the existing system in place. This is the lower-cost, lower-disruption option in the short term.
What Is Involved
- Check the system version, firmware and fitted cards to confirm SIP capability
- Review current licensing and determine whether additional SIP channel licences are needed
- Configure SIP trunks via the system's web maintenance console
- Port existing phone numbers from BT/Openreach to the SIP provider
- Test inbound, outbound, call routing, voicemail and all configured features
- Go live: old ISDN lines ceased, SIP trunks take over
Considerations
- SIP migration buys time but does not resolve the hardware support issue
- Licencing costs can add significantly to the migration cost on some NEC platforms
- Existing proprietary handsets continue working but cannot be reused if the system is eventually replaced
- NEC hardware spare parts will become harder and more expensive to source over time
Option 2: Full Cloud VoIP Replacement
Replacing the NEC system entirely with a hosted cloud VoIP platform removes the hardware dependency, eliminates maintenance complexity and opens up modern features that on-premise PBX systems cannot easily provide.
What You Gain
- No on-site PBX hardware to maintain or source parts for
- Mobile apps so staff can use their business number anywhere
- Call recording for compliance and training
- Auto-attendant, call queues and routing flexibility
- Microsoft Teams integration where needed
- Add or remove users without buying expansion cards
- Remote workers supported without additional hardware
- Predictable monthly cost per user
What Happens to NEC Handsets
NEC proprietary digital handsets (DT3 and DT4 series) cannot be reused on other manufacturers' hosted VoIP platforms. They are specific to NEC hardware.
Some NEC SIP handsets (DT920 and certain DT900 series models) may work on standards-based SIP platforms, but compatibility needs to be tested before assuming it will work. In most cases, replacing with Yealink or equivalent SIP handsets is simpler and gives better long-term results than trying to reuse NEC hardware.
Cost Guidance
- Hosted VoIP: typically £8 to £15 per user per month including features
- New handsets: from £60 to £200 per handset depending on model
- Number porting: typically free or included in setup
- Setup and configuration: varies by system size and complexity
When to Choose SIP Migration vs Full Replacement
SIP trunking makes more sense when:
- The system is in good condition and recently serviced
- Licencing supports the required SIP channel count without significant extra cost
- The business is happy with current features and does not need mobile apps or modern integrations
- Budget is limited and a lower-cost short-term solution is needed
Full hosted VoIP replacement makes more sense when:
- The system is aging or has recurring faults
- Licencing costs would make SIP migration expensive
- Mobile working, remote staff or modern call routing features are needed
- The business wants to remove hardware dependency entirely
- Handsets are due for replacement anyway
Getting a Proper Assessment
The starting point for any NEC migration is a proper assessment of what you have. The system version, cards, licences, handset models and current configuration all affect the options and costs. Two businesses with what looks like the same NEC system can face very different migration paths depending on what is inside the cabinet.
We provide a free assessment that covers:
- System model and firmware version
- Fitted cards and SIP capability
- Licensing review
- Handset inventory and reuse assessment
- Broadband suitability for SIP/VoIP
- Number porting requirements
- Recommendation with cost estimate for both options
Book a Free NEC Assessment
Ring us and tell us what NEC system you have. We will arrange a visit or remote assessment, check the system properly, and give you a clear recommendation with costs. No obligation.
Frequently Asked Questions
Is NEC SL2100 end of life?
NEC exited the unified communications market in 2024. While SL2100 hardware continues to function, manufacturer support is no longer guaranteed and spare parts are becoming scarce. The ISDN lines most NEC systems depend on are also being switched off in January 2027.
Can the NEC SL2100 be migrated to SIP trunking?
Yes, the SL2100 supports SIP trunking. SIP capability and available channel capacity depends on the system version, the cards fitted and the current licensing. A system check is needed before committing to this approach.
What NEC handsets can be reused on a VoIP platform?
NEC proprietary digital handsets (DT3 and DT4 series) cannot be reused on a different manufacturer's hosted VoIP platform. Some NEC SIP handsets (such as the DT920 SIP series) may be compatible with third-party platforms, but this requires testing. In most cases, replacing with Yealink SIP handsets is simpler and more cost-effective.
What is the difference between NEC SL2100 and SV9100?
The SL2100 is designed for smaller businesses (typically up to 100 extensions). The SV9100 is a larger platform supporting hundreds of extensions and multiple sites. Both face the same ISDN switch-off deadline and the same hardware support concerns following NEC's market exit, but the migration complexity and cost differ significantly.