What is Being Switched Off and When?

In January 2027, BT Openreach will permanently decommission the entire ISDN and analogue telephone network across the United Kingdom. This is not a gradual phase-out or a regional pilot — it is a complete, irreversible shutdown of the copper-based telephone infrastructure that has served British businesses for decades. Every ISDN circuit and every analogue phone line in the country will cease to function.

Here is exactly what is being switched off:

ISDN30 (PRI — Primary Rate Interface)

ISDN30 delivers 30 simultaneous call channels per circuit. It is the backbone of medium and large business telephony — used by organisations with 30 or more extensions, call centres, and multi-line environments. Each PRI circuit provides 30 concurrent call paths, meaning a business with two PRI circuits can handle 60 simultaneous calls. ISDN30 PRI is typically connected to a PBX system via a dedicated PRI card (such as the Avaya IP500 PRI card or Panasonic PRI trunk card). Being permanently switched off January 2027.

ISDN2e (BRI — Basic Rate Interface)

ISDN2e provides 2 simultaneous call channels per circuit. It is the standard connection for small businesses that need more than a single phone line but don't require the capacity of a full PRI. Commonly used for small offices with a handful of extensions, fax machines, and card payment terminals. Many small Panasonic and other PBX systems across Northern Ireland are connected via ISDN2e BRI. Being permanently switched off January 2027.

Analogue Lines (PSTN)

Traditional single-channel phone lines — one call at a time per line. These are the most basic form of telephone connection and are used for individual phones, fax machines, intruder alarm systems, lift emergency phones, door entry systems, CCTV diallers, franking machines, and card payment terminals. If you have a device plugged into a standard phone socket on the wall, it is almost certainly running on an analogue line. Being permanently switched off January 2027.

Who is Affected?

If your business uses any form of traditional telephone line, you are affected. Specifically, this impacts businesses with:

• Avaya IP Office or Avaya Aura systems connected via ISDN30 PRI cards — the PRI card in your Avaya system will have nothing to connect to
• Panasonic NS700/NSX systems connected via ISDN30 PRI cards or ISDN2e BRI cards — the trunk cards in your Panasonic will become redundant
• Any PBX system using ISDN trunks — this includes Mitel, NEC, Samsung, Siemens/Unify, LG-Ericsson, and any other manufacturer
• Analogue lines for fax machines — traditional fax over copper will no longer work
• Analogue lines for alarm systems — intruder alarms that dial out over a phone line will lose their communication path
• Analogue lines for lift emergency phones — legally required emergency phones in lifts that use analogue lines will stop working
• Analogue lines for door entry systems — intercom and door release systems connected via phone lines
• Analogue lines for CCTV diallers — legacy CCTV systems that alert via phone line
• Analogue lines for card payment terminals — older chip-and-pin machines that dial out over a phone line
• Multi-site businesses with ISDN between locations — inter-site ISDN links will be severed
• Call centres running ISDN30 — high-volume call environments that depend on PRI for call capacity

The simple test: if you have a phone system with physical ISDN cards plugged into it, you are affected. If you have any device connected to a traditional phone socket on the wall, you are affected. There are no exceptions.

Your Two Migration Options

Every affected business has two clear paths forward. The right choice depends on your current system, your budget, and your long-term plans.

Option A: SIP Trunking — Keep Your Existing PBX

SIP trunking replaces your ISDN lines with internet-based voice connections. Your PBX system stays exactly where it is — only the lines coming into it change. Think of it as swapping the road that leads to your building, while the building itself remains untouched.

• How it works: The ISDN PRI or BRI card inside your PBX is removed (or simply deactivated) and a SIP trunk is configured in its place. The SIP trunk connects your PBX to a VoIP provider over your broadband connection
• Avaya IP Office supports SIP trunking natively — remove the ISDN30 PRI card, configure the SIP trunk via Avaya Manager software, and your system continues operating as normal
• Panasonic NS700/NSX supports SIP trunking — remove the ISDN cards, add SIP trunk configuration via the Panasonic web interface, and all existing functionality is preserved
• Everything stays: Your existing handsets, extension numbers, call flows, hunt groups, voicemail, and auto-attendant all continue working exactly as before
• Speed: Typically the fastest migration path — a straightforward SIP trunk migration can be completed in a single day for most systems
• Bandwidth requirement: You need decent broadband — a minimum of 1Mbps per simultaneous call. A 10-channel SIP trunk needs at least 10Mbps of reliable upload speed
• Number porting: All your existing phone numbers are ported to the SIP trunk provider. Your customers continue calling the same numbers they always have
• Cost saving: SIP trunks typically cost £3-8 per channel per month, compared to £15-25 per channel for ISDN. That is an immediate saving on line rental alone, often 50-70% less
• Flexibility: Unlike ISDN30 which locks you into 30-channel increments, SIP trunks can be provisioned in any quantity — 5, 12, 23, whatever your business actually needs

The downside: Your PBX hardware is aging and will eventually need replacing. SIP trunking buys you time and saves you money on line rental, but it does not solve the long-term problem of maintaining legacy hardware. At some point, the PBX itself will reach end of life.

Option B: Hosted VoIP — Replace Everything with Cloud

Hosted VoIP removes the PBX entirely and moves your entire phone system to the cloud. There is no on-premise hardware to maintain — everything is managed by Drakos Systems in our data centres.

• How it works: Your old PBX is decommissioned. Modern IP handsets (Yealink) or softphone apps are deployed to every user. All call routing, voicemail, and features are managed in the cloud
• Modern features included: Mobile apps for iOS and Android, call recording, Microsoft Teams integration, CRM connectivity, AI-powered call transcription, video conferencing, and instant messaging
• No upfront capital cost: Monthly per-user subscription model — no large lump sum for hardware. Handsets can be included in the monthly fee or purchased outright
• Scalability: Add or remove users as your business grows or contracts. No need to buy additional PBX cards or licenses in bulk
• Work from anywhere: Hosted VoIP works from the office, from home, or from a mobile phone. Every user gets the same experience regardless of location
• Future-proof: The system is always on the latest software version. New features are added automatically without engineer visits or hardware upgrades
• Fully managed: Drakos Systems handles all maintenance, updates, and support. If something goes wrong, we fix it remotely — no waiting for an engineer to visit your premises
• Number porting: All existing numbers are ported to the hosted platform, just as with SIP trunking

The downside: Higher monthly cost per user than SIP trunking (since you are paying for the entire platform, not just the lines). Staff will need retraining on new handsets and the new system interface. There is also a dependency on your broadband connection — if the internet goes down, so do your phones (though 4G failover can mitigate this).

Avaya ISDN to SIP Migration

If you have an Avaya IP Office system currently connected via ISDN30 PRI, here is exactly what the migration to SIP involves:

• Compatibility: Avaya IP Office 500 V2 supports SIP trunking from software release R9.1 onwards. If your system is running an older release, a software upgrade may be required before SIP trunks can be configured
• Hardware change: The IP500 PRI card (the physical ISDN30 card inside your Avaya control unit) is removed. No replacement card is needed — SIP trunks are configured in software via the Avaya IP Office Manager application
• Flexible capacity: With ISDN30, you were locked into 30-channel increments. With SIP, you can provision exactly the number of channels you need — 10, 15, 22, or any number that matches your actual call volume
• Handsets continue working: All existing Avaya digital phones (1400 series, 9500 series) and IP phones (J100 series, 9600 series) continue to work without any changes. Your users will not notice any difference
• Features transfer: Call routing, hunt groups, voicemail, auto-attendant, short codes, and all programmed call flows transfer directly to the SIP trunk. No reprogramming of user-facing features is required
• Phased migration for larger systems: For Avaya systems with 100+ extensions, we recommend a phased approach — run SIP and ISDN in parallel during the transition period. This allows thorough testing before the ISDN lines are fully decommissioned
• Avaya Cloud Office (ACO): If you want to move to a full cloud solution while staying within the Avaya ecosystem, Avaya IP Office can be migrated to Avaya Cloud Office — a hosted UCaaS platform powered by RingCentral
• Full replacement option: Alternatively, replace the Avaya system entirely with Drakos hosted VoIP for a fully managed solution with no Avaya licensing costs, no annual maintenance contracts, and modern features included as standard

We handle the complete Avaya migration end to end: initial audit of your current system, SIP trunk provisioning with a reliable UK provider, number porting, Avaya Manager configuration, thorough testing of all call routes and features, go-live support, and ongoing management.

Panasonic ISDN to SIP Migration

If you have a Panasonic NS700 or NSX system connected via ISDN, here is what the migration looks like:

• Compatibility: Both the Panasonic NS700 and NSX series fully support SIP trunking. These systems were designed as hybrid platforms capable of handling both traditional ISDN and modern SIP connections
• Hardware change: The ISDN2e BRI cards or ISDN30 PRI cards inside your Panasonic system are removed or deactivated. SIP trunk parameters are configured via the Panasonic web-based management interface
• Existing phones keep working: All Panasonic digital phones (KX-DT series) and IP phones continue to function as normal. Your staff will not need to learn new handsets or change any of their habits
• DECT cordless phones: If your business uses Panasonic DECT cordless handsets (very common in hospitality, retail, warehouses, and healthcare), these continue working without any changes. Only the trunk connection changes — the internal phone system is unaffected
• Configuration: SIP trunk setup on Panasonic systems is done through the web-based programming interface. We configure the SIP provider credentials, codec settings, and call routing to match your existing setup
• Common in Northern Ireland: Panasonic systems are particularly widespread in hospitality (hotels, restaurants), retail, small offices, and medical practices across Northern Ireland. We have migrated hundreds of Panasonic systems from ISDN to SIP
• Full replacement option: If your Panasonic system is aging or you want access to modern features like mobile apps, call recording, and Microsoft Teams integration, we can replace the Panasonic entirely with Drakos hosted VoIP — zero on-site hardware, zero maintenance, and a modern feature set

We handle the complete Panasonic migration including system audit, SIP trunk provisioning, number porting, configuration, testing, go-live support, and staff training on any new features.

What About Analogue Lines?

Analogue lines are easy to forget about because they often connect devices that sit quietly in the background — until they stop working. Every analogue line in your business needs to be identified and migrated before January 2027. Here is how to handle each common use case:

Fax Machines

Traditional fax machines that dial out over an analogue line will stop working. Replace with an email-to-fax or fax-over-IP (FoIP) service. These services give you a fax number that receives faxes as email attachments (PDF) and allows you to send faxes from your computer. No physical fax machine needed. If you must keep a physical fax machine, a SIP ATA (analogue telephone adapter) can connect it to a VoIP line.

Alarm Systems

Many intruder alarm panels use an analogue phone line to communicate with the monitoring centre (sending alarm signals via the PSTN). Most modern alarm panels support IP or 4G reporting as an alternative. Contact your alarm monitoring company to upgrade the communicator module in your alarm panel. This is typically a straightforward swap of the communication module — the alarm panel itself and all sensors remain unchanged.

Lift Emergency Phones

Lifts are legally required to have an emergency phone that connects to a monitoring service. Many of these use analogue lines. Replace with a 4G GSM gateway or an IP-based lift phone. Several manufacturers now produce lift phones with built-in 4G SIM connectivity, eliminating the need for any phone line. Your lift maintenance company can advise on the best replacement for your specific installation.

Door Entry Systems

Intercom and door release systems that dial an analogue phone line to notify staff of visitors. SIP-compatible door entry panels are available from manufacturers like 2N, Akuvox, and Grandstream — these connect directly to your SIP trunk or hosted VoIP system. Alternatively, a 4G adapter can bridge the gap for legacy door entry panels that cannot be replaced immediately.

Card Payment Terminals

Older chip-and-pin machines that process transactions by dialling out over an analogue line. Most modern payment terminals use 4G or broadband connectivity instead. Contact your payment provider (Worldpay, Barclaycard, Square, SumUp, etc.) for an upgraded terminal. In most cases, the provider will swap the terminal at no cost as part of their standard equipment refresh cycle.

CCTV Systems

Legacy CCTV systems that send alerts or allow remote viewing via an analogue phone line. Modern CCTV is already IP-based in most installations. If you still have analogue CCTV that relies on a phone line for remote access, this is an excellent opportunity to upgrade to a modern IP camera system with app-based remote viewing and cloud recording.

Franking Machines

Some franking machines download postage credits via an analogue phone line. Contact your franking provider (Pitney Bowes, FP Mailing, Neopost/Quadient) for an IP-enabled model or a connectivity upgrade. Most providers have already transitioned their fleet to broadband-connected machines.

The Timeline — What You Should Do Now

With less than a year until the switch-off, every month counts. Here is a realistic timeline for getting your business migrated safely:

Now — April 2026

Audit everything. Identify every ISDN circuit and every analogue line your business has. Check every phone socket, every device connected to a phone line, every BT bill. Document what each line is used for — main phone system, fax, alarm, lift, door entry, card terminal, CCTV. Get quotes for both SIP trunking (to keep your PBX) and hosted VoIP (to replace it). Assess your broadband — is it fast enough and reliable enough for voice traffic?

May — June 2026

Make your decision. Choose between SIP trunking and hosted VoIP based on the quotes, your budget, and your long-term plans. Order a broadband upgrade if your current connection is not sufficient for voice traffic. Begin the number porting process — this can take 2-4 weeks depending on the provider and the complexity of the port. Order any replacement equipment for analogue devices (4G alarm communicators, IP lift phones, new payment terminals).

July — September 2026

Complete the migration. Have your SIP trunks installed and configured, or your hosted VoIP system deployed. Test thoroughly — make test calls to every number, check every hunt group, verify voicemail, test fax, confirm alarm reporting, check lift phones. Train staff on any new equipment or features. Migrate all analogue devices to their IP or 4G replacements.

October — December 2026

Buffer period. This is your safety net. Use these months to resolve any issues that emerged during migration. Confirm that all analogue devices have been successfully migrated. Run parallel systems if possible — keep ISDN active alongside SIP until you are 100% confident everything works. Conduct a final audit to ensure nothing has been missed.

January 2027

ISDN and analogue lines are switched off. If you have not migrated, your phones stop working. No incoming calls. No outgoing calls. No fax. No alarm reporting. No lift emergency phone. Nothing. There is no extension, no grace period, and no workaround.

How Much Will Migration Cost?

Cost is the first question every business asks, and rightly so. Here is realistic pricing guidance based on the hundreds of migrations we have completed:

Option A: SIP Trunking (Keep Your PBX)

• Configuration and setup: £500 — £2,000 depending on the complexity of your system, the number of lines, and whether a software upgrade is needed
• Monthly SIP trunk cost: £3 — £8 per channel per month (compared to £15 — £25 per ISDN channel)
• Number porting: Typically free or included in the SIP trunk setup
• Broadband upgrade (if needed): Varies depending on your location and provider — leased line options from £150/month for guaranteed bandwidth

Example: A business with 30 ISDN channels (one PRI) currently paying £600/month in ISDN line rental could migrate to a 30-channel SIP trunk for approximately £150-240/month — saving £360-450 per month, every month. The one-off setup cost is typically recovered within 2-4 months from line rental savings alone.

Option B: Hosted VoIP (Replace Your PBX)

• Setup and deployment: £0 — £5,000 depending on the number of users, handset choices, and complexity of the migration. Many providers offer zero-cost setup on longer contracts
• Monthly per-user cost: £8 — £15 per user per month, including all features, updates, and support
• Handsets: Yealink IP phones from £60-250 per handset, or included in the monthly subscription on certain plans
• Number porting: Typically free or included

Example: A 20-user business replacing an aging PBX with hosted VoIP might pay £200-300/month for the complete phone system — including all features, mobile apps, call recording, and ongoing support. No maintenance contracts, no PBX hardware to repair, no annual licensing fees.

The Bottom Line

Most businesses save money after migration. The combination of lower line rental (SIP vs ISDN), eliminated maintenance contracts (hosted VoIP), and reduced hardware costs means the migration typically pays for itself within months, not years. The ISDN switch-off is not just a forced migration — it is an opportunity to reduce your telecoms costs significantly.

Why Businesses Choose Drakos Systems for ISDN Migration

• 20+ years experience with Avaya and Panasonic systems: We don't just sell SIP trunks — we understand the PBX hardware inside and out. We know the Avaya Manager software, the Panasonic web interface, the trunk card configurations, and the quirks of every system version
• End-to-end service: We handle everything — initial audit, broadband assessment, SIP trunk provisioning, number porting, PBX configuration, testing of every call route and feature, go-live support, and ongoing management
• Belfast-based team: Our engineers are based in Belfast with on-site support available across all of Northern Ireland. We are not a remote-only provider — we come to your premises when needed
• ISO 27001 certified: Our information security management is independently audited and certified. Your business communications are in safe hands
• Both options available: We offer SIP trunking (to keep your PBX running) and fully managed hosted VoIP (to replace it entirely). We will recommend what is genuinely right for your business — not what generates the highest commission
• No pressure: We provide honest, straightforward advice. If your Avaya or Panasonic system has years of life left and SIP trunking is the sensible choice, we will tell you that. If your system is end-of-life and hosted VoIP makes more sense, we will tell you that too
• Proven track record: We have migrated businesses of all sizes across Northern Ireland — from 5-user offices to 200+ seat contact centres. We know what works and what to watch out for

Frequently Asked Questions