Quick Answer: The Ofcom and Openreach PSTN switch-off deadline is 31 January 2027. All analogue and ISDN lines will cease. Resellers can monetise this through PSTN audits (£500-£1,500 per site), migration project management (£2,000-£5,000), and ongoing SIP trunk sales (£15-£25/month per trunk). Device-specific migrations (alarms, lifts, EPOS) have highest project value. Start auditing customer sites now. Most projects take 6-12 weeks; urgency peaks in Q4 2026.
PSTN Switch-Off Timeline and Audit Inventory
The deadline is fixed: 31 January 2027. Resellers must audit all customer analogue and ISDN dependencies and plan migrations immediately. This table structures the audit process.
| Timeline Phase | Key Milestone | Ofcom/Openreach Actions | Reseller Action Items | Customer Action Items |
|---|---|---|---|---|
| Now (Q1 2026) | Awareness and Planning | Ofcom publishes switch-off support materials. Openreach offers free audits (limited availability). | Launch PSTN audit programme. Contact all customers. Schedule on-site surveys. Create migration playbooks for vertical markets (retail, healthcare, hospitality). | Understand PSTN usage and dependencies. Identify all analogue/ISDN lines and devices. |
| Q2 2026 | Assessment Phase | Openreach offers ISDN replacement consultations. BT and major carriers launch SIP migration programmes. | Complete customer audits. Develop project plans and cost estimates. Secure customer commitments. Procure SBC and gateway hardware. | Approve migration plans and budgets. Begin internal stakeholder alignment (IT, ops, security). |
| Q3 2026 | Rollout Phase | Peak migration activity. Openreach may have backlog for complex migrations. | Deploy SIP infrastructure in parallel with PSTN. Test calling, emergency services, device interop. Train customer staff. | Conduct user acceptance testing. Validate emergency call routing. Train end users. |
| Q4 2026 | Final Cutover Phase | Openreach prioritises remaining migrations. Last-minute notices for incomplete migrations. | Execute cutover operations. Monitor for issues. Decommission PSTN lines 30-60 days before deadline. | Complete final calls to old PSTN numbers. Document new SIP endpoints. Plan for any rollback scenarios. |
| 31 January 2027 | Hard Deadline | All PSTN lines cease. Analogue and ISDN disconnected nationwide. | Provide 24/7 support to any customers with unexpected issues. Handle escalations to SIP trunk provider. | All calls routed via SIP trunk or cloud voice. Analogue/ISDN lines offline. |
Customer PSTN Inventory: Audit Checklist
This checklist guides a systematic on-site audit. Document all dependencies before designing the migration.
| Equipment / Service Category | Audit Question | Discovery Actions | Risk Assessment | Migration Complexity |
|---|---|---|---|---|
| Desk Phones and Voice Users | How many desk phones are in use? Are they SIP-capable or POTS-only? | Walk the office. List all phones by model. Check serial number against vendor specs. Test SIP compatibility on test system. | Low. Most phones from 2015 onwards are SIP-capable. Legacy phones (pre-2010) may need replacement. | Low. Replace or upgrade firmware. Testing: 1 week per 100 users. |
| PBX / Phone System | What PBX/phone system is installed? Is it SIP-capable? | Identify manufacturer (Avaya, Cisco, Siemens, NEC, Panasonic). Check PBX model and software version. Verify SIP licence availability from vendor. | High for legacy PBX. Low for modern IP PBX. Determine upgrade vs. replace vs. hybrid (SBC) strategy. | Medium-High. PBX upgrade or SBC integration requires vendor engineering. Timeline: 2-4 weeks for testing. |
| Security Alarm Systems | Are there stand-alone alarm systems dialling to monitoring centres? Are they analogue-dependent? | Walk all areas. Locate alarm panels. Check labels and documentation. Contact monitoring centre to confirm line dependencies. | Very High. Alarms cannot function without PSTN or SIP alternative. If misconfigured, business is uninsured. | High. Requires site survey, gateway selection, monitoring centre testing. Timeline: 3-6 weeks including certification. |
| Lifts / Elevators | Are lift emergency phones connected to analogue lines? Dual-line requirement? Emergency service integration? | Visit lift machine rooms. Document all phone connections. Check lift maintenance logs for phone module specs. Consult lift engineer. | Very High. Lift phones must work for emergency calls by law. Failure = liability and insurance violation. | Very High. Requires lift engineering certification and coordination with lift maintainer. Timeline: 4-8 weeks including testing and certification. |
| EPOS / Payment Terminals | Do EPOS systems dial out for payment authorisation? Are they analogue or modem-dependent? | Speak to retail operations. Identify EPOS vendor and model. Check payment processor (card networks) requirements. Test EPOS on IP network. | High. EPOS failure stops payments. If not migrated, till system may be non-functional. | High. Requires EPOS vendor support and payment processor coordination. Timeline: 2-4 weeks including testing and training. |
| Fax Machines | Are there dedicated fax machines or fax software? Are they analogue-dependent? | Locate all fax devices. Check usage metrics (pages/month sent and received). Determine if faxing is critical or archaic. | Low. Fax is declining. Most organisations can migrate to cloud fax or stop faxing entirely. | Low. Deploy T.38 SIP gateway or cloud fax service. Timeline: 1-2 weeks including testing. |
| Modems and Data Connections | Are any modems or data lines in use? (Older legacy systems, backup internet, speciality hardware). | Interview IT staff. Audit network diagram for modem connections. Identify purpose and criticality. | Medium. Most modems are obsolete, but speciality hardware (medical devices, industrial controls) may depend on them. | Medium. Replace with broadband/VPN alternative or dedicated connectivity. Timeline: 2-4 weeks depending on hardware replacement needs. |
| Backup and Redundancy Lines | Are there unused or backup PSTN lines that can be decommissioned? | Walk site. Ask staff about unused lines. Check telephone bills for listed numbers. Reconcile with audit findings. | Low. Backup lines are often forgotten and can simply be decommissioned. | Low. Decommission via Openreach. Timeline: 1-2 weeks administrative work. |
| Multi-site and Wide-Area Considerations | If customer has multiple sites, are they trunk-connected? Does HQ route calls for remote offices? | Interview IT/ops. Review WAN diagram. Understand inter-site calling patterns. | High if sites rely on analogue trunk routing. Medium if modern IP WAN. | High for legacy trunk-based WAN. Multi-site SIP architecture is complex. Timeline: 4-8 weeks design and implementation. |
Device Migration Path Matrix
For each device type, there are multiple migration options. This matrix shows the recommended path by device and customer profile.
| Device Type | Current PSTN Dependency | Option A (Preferred) | Option B (Fallback) | Option C (Last Resort) | Cost Estimate (A/B/C) | Timeline (A/B/C) |
|---|---|---|---|---|---|---|
| Desk Phones | Analogue/ISDN line per phone. | Replace with SIP phone (Yealink, Polycom, Cisco). IP network required. | Upgrade existing phone firmware to SIP (if vendor supports). | Deploy analogue gateway per phone set (inefficient). | A: £150-£300/phone. B: £0-£100 (firmware). C: £200-£400/gateway. | A: 1-2 weeks. B: 1 week. C: 2-3 weeks. |
| PBX System | Analogue/ISDN trunks feeding PBX. | Migrate to cloud voice (Teams Phone, Avaya Cloud). Decommission PBX. | Add SBC + SIP trunk to existing PBX. Hybrid model (PBX + cloud). | Upgrade PBX to SIP-capable version (Avaya, Cisco hardware upgrade). | A: £5,000-£15,000 (cloud implementation). B: £3,000-£8,000 (SBC + SIP). C: £10,000-£25,000 (PBX upgrade). | A: 4-8 weeks. B: 2-4 weeks. C: 6-12 weeks. |
| Alarm System | Dedicated analogue line for monitoring centre dial-out. | Deploy SIP gateway (Grandstream, EDPACS) in parallel with monitoring centre. Test certified. | Deploy PSTN/SIP hybrid gateway with mobile backup (4G modem). | Switch to cloud-based alarm service (ARC provider with VoIP). Requires insurer approval. | A: £500-£1,200 (gateway) + £800-£1,500 (install + cert). B: £700-£1,500 (hybrid gateway). C: £1,500-£3,000 (cloud service setup). | A: 4-6 weeks. B: 4-6 weeks. C: 6-8 weeks (insurer approval). |
| Lift Phone | Dual analogue lines for emergency call and building owner notification. | Replace lift phone module with SIP-capable module (requires lift engineering certification). | Deploy SIP gateway in lift machine room. Maintain dual redundancy (SIP + mobile backup). | Install mobile phone in lift (not recommended; no legal compliance guarantee). | A: £1,500-£3,000 (module + installation). B: £800-£1,500 (gateway + installation). C: £300-£600 (mobile, but risky). | A: 6-10 weeks (lift engineering slots). B: 4-6 weeks. C: 1-2 weeks (not recommended). |
| EPOS System | Dedicated analogue or modem connection for payment authorisation (some modern EPOS over IP). | Upgrade EPOS to modern IP-capable system (work with EPOS vendor and payment processor). | Deploy PSTN/SIP gateway to preserve old EPOS. Interim solution pending EPOS upgrade. | Migrate to mobile 4G backup or pin-pad reader (if payment processor supports offline mode). | A: £3,000-£8,000 (EPOS hardware + setup). B: £500-£1,200 (gateway). C: £500-£1,000 (mobile + reader). | A: 4-8 weeks (EPOS deployment + PCI compliance). B: 2-4 weeks. C: 2-3 weeks. |
| Fax Machine | Analogue line dedicated to fax. | Migrate to cloud fax service (eFax, RingCentral Fax, Avaya Fax). No hardware needed. | Deploy T.38 SIP gateway (Grandstream GWN). Preserve existing fax machine. | Discontinue faxing entirely (most orgs moving to digital document flow). | A: £10-£20/month (cloud fax SaaS). B: £200-£400 (gateway + setup). C: £0. | A: 1 week (SaaS onboarding). B: 1-2 weeks. C: 1-2 weeks (process change only). |
Risk Assessment and Contingency Planning
Some migrations carry higher risk. This table identifies risk factors and mitigation strategies.
| Risk Factor | Severity | Affected Device Types | Mitigation Strategy | Reseller Action |
|---|---|---|---|---|
| Emergency Call Failure (999) | Critical | Lifts, alarms, all phones. | Test emergency routing before cutover. Maintain SIP provider SLA guarantee (99.5% minimum). Document testing results. | Include 999 testing in migration scope. Obtain written confirmation from SIP provider that emergency routing is certified. Provide customer with documented testing evidence. |
| Device Incompatibility (PBX or phone unsupported) | High | PBX systems, legacy phones, alarms, lifts. | Audit equipment compatibility early. If unsupported, plan replacement well in advance (6-8 weeks lead time). | Create compatibility matrix before quoting. If replacement required, identify cost and timeline impact upfront. Obtain vendor confirmation of SIP support. |
| Monitoring Centre Certification Delay (alarm, lift) | High | Alarms, lifts. | Engage monitoring centre early (Q1 2026). Provide technical specs for SIP gateway. Allow 4-6 weeks for centre certification and testing. | Contact monitoring centre on customer’s behalf. Obtain written certification path. Document timeline assumptions. |
| Lift Engineering Scheduling Bottleneck | High | Lifts. | Book lift engineer slots early (Q2 2026). Complex lifts may have 8-week backlogs. Plan for worst-case scenario. | Identify lift maintainer. Request engineering assessment and availability calendar by Q2. Build buffer into project timeline (add 4-6 weeks). |
| EPOS Payment Processor Constraints | Medium | EPOS systems. | Contact payment processor (card network) early. Confirm IP support and any compliance changes (PCI-DSS). Some processors may require phone support. | Conference call with customer, EPOS vendor, and payment processor. Document all requirements. Some EPOS may need to stay on SIP gateway during processor transition. |
| Customer Resistance / Budget Constraints | High | All device types. | Provide early cost estimates and ROI analysis. Show lifecycle cost (PSTN rising costs vs. one-time SIP migration). Offer staged payment or leasing options. | Develop 3-year TCO comparison document. Quantify PSTN cost increase (Openreach/BT raising PSTN rates). Highlight compliance risks and insurance implications if not migrated. |
| Connectivity Quality Insufficient (poor broadband) | Medium-High | All devices depending on VoIP quality. | Pre-assess customer broadband speed and stability (use speed test). If <20Mb or contended, recommend upgrade to leased line or FTTP. May delay migration. | Include broadband assessment in audit. If upgrade needed, coordinate with ISP / Openreach. Add connectivity upgrade cost to migration estimate. Allow 4-6 weeks for broadband provisioning. |
| Lack of Internal IT Support (customer) | Medium | All systems if customer has no IT resource. | Offer managed migration service. Provide post-migration support retainer (e.g., £300-£600/month) including helpdesk and system monitoring. | Scope managed services and ongoing support in project proposal. Highlight value of outsourced IT dependency management. |
Frequently Asked Questions
If I don’t migrate by 31 January 2027, what happens?
Ofcom will force Openreach and other carriers to switch off all PSTN lines on the deadline date. Your customer’s analogue and ISDN lines will stop working. No incoming or outgoing calls possible. Business interruption is severe. There is no grace period.
Do I need to do a full audit of my customer base or just PSTN-heavy customers?
Audit all customers who have any analogue or ISDN lines. This includes SMEs, offices, retail, healthcare, hospitality, manufacturing. If they’ve had a business phone for more than 5 years, assume they have PSTN dependencies. Proactive audit builds trust and revenue opportunity.
What if a customer’s PBX manufacturer goes out of business or ends SIP support?
This is a real risk with legacy vendors (some Siemens, Panasonic models). Identify the vendor and check their SIP roadmap now (Q1 2026). If unsupported, cloud voice migration or SBC option is required. Include this risk in your audit report.
Can I charge the customer for the PSTN audit?
Yes. Charge £500-£1,500 per site depending on complexity (single site vs. multi-site, device count). Audit typically takes 4-8 hours on-site plus report writing. If customer buys migration services, credit audit fee against project cost.
How do I handle a customer with a 2-year contract on ISDN lines?
BT and Openreach will honour early termination requests for PSTN lines if customer is migrating to SIP. The contract becomes void as PSTN service ceases. Help customer negotiate early cancellation with current carrier. May incur early exit fee, but typically waived for switch-off circumstances.
Do lifts and alarms have to be SIP-certified by a specific body?
Lifts must meet BS EN 81 standards (UK lift safety). SIP integration must be certified by a lift engineer. Alarms must be certified by the monitoring centre (e.g., Alarm Receiving Centre). These are legal requirements. You cannot self-certify. Always involve the relevant specialist.
Sources
Ofcom PSTN Switch-Off Programme and Timeline
UK Government PSTN Switch-Off Information
Openreach PSTN Switch-Off and Migration Support
BT PSTN Switch-Off and SIP Migration
ISP Review PSTN Switch-Off Coverage and News
Partner Playbook: PSTN Switch-Off Audit and Migration Services Roadmap
| Quarter | Key Milestone | Reseller Activity | Sales Target | Revenue Opportunity | Status |
|---|---|---|---|---|---|
| Q1 2026 | Audit Phase Launch | Contact all customers. Schedule on-site audits. Create audit template and playbooks. | Complete audits on 30% of customer base. Secure 10 signed migration proposals. | Audit fees: £5,000-£8,000. Pre-sales: £20,000-£30,000. | [ ] |
| Q2 2026 | Design and Procurement Phase | Complete remaining audits. Design migrations. Procure hardware. Get monitoring centre and lift engineer certifications started. | Complete 80% of customer audits. Secure 20 migration projects (£30,000+ value). Start 5 complex projects (lift, alarm, multi-site). | Design and procurement: £30,000-£50,000. Hardware sales: £40,000-£60,000. | [ ] |
| Q3 2026 | Implementation Phase | Execute migrations in parallel across customer base. Monitor QoS. Train customer staff. Test emergency calling. | Complete 50% of migration projects. Launch 10 new projects. High-support period. | Implementation services: £80,000-£120,000. SIP trunk activation: £50 trunks x £20 = £1,000/month ongoing. | [ ] |
| Q4 2026 | Cutover and Final Phase | Complete all migrations before 31 Jan deadline. Handle escalations and post-cutover support. | Complete 95% of projects. Maintain 24/7 support availability during peak cutover weeks. | Final implementation: £50,000-£70,000. Ongoing support retainers: £300-£600/customer/month (100+ customers). | [ ] |
| 2027 Onwards | Steady-State Support and Upsell | Manage SIP trunk operations. Upsell managed services, call recording, compliance features. Decommission any remaining PSTN. | Retain 95%+ of migrated customers. Achieve 30% attach rate on managed services. Annual SIP trunk revenue: £200,000+. | Ongoing MRR from SIP trunks: £50k/month. Support and managed services: £30k/month. | [ ] |
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