How to Switch Leased Line Provider Without Downtime (2026 UK Guide) Quick Answer
You can switch leased line providers without downtime by installing a parallel circuit from your new provider while keeping your old line active, then migrating your network during a planned change window. Most UK businesses complete the switch safely within 45–90 days, and downtime can be reduced to under 2 minutes or avoided entirely with dual connections or 4G/5G failover.
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Contents:
Why UK Businesses Switch Leased Line Providers in 2026
How to Switch Leased Line Providers Without Downtime
Downtime Risk Comparison
Costs to Consider When Switching Providers
Can You Keep Your Existing IP Address Range?
Switching Leased Lines When Moving Office
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Authored by: Ally Cox (Business Technology & B2B Services Specialist 10+ Years’ Experience)
Reviewed by: James Ward (Telecoms Specialist, 12+ Years Experience)
Last Updated: January 2026
Why UK Businesses Switch Leased Line Providers in 2026 From our experience, the top reasons include:
Price increases at contract renewal
Better speeds or FTTP availability
Poor customer support
Upgrading to hybrid or remote-first infrastructure
Need for improved SLAs and fix times
Moving office
Leased lines are now highly competitive in the UK, with entry pricing starting at £139–£179/month for 100Mbps and £189–£350/month for 1Gbps. So switching can save thousands over a 36-month contract.
How to Switch Leased Line Providers Without Downtime (Step-by-Step) Step 1: Make sure to order your leased line earlier than you need
Leased line installation takes 45–90 days depending on:
Site surveys
Wayleaves
ECCs (Excess Construction Charges)
Fibre availability near your premises
So, that’s why you should order the new line before cancelling your existing contract.
Step 2: Keep your existing line active while you wait
This is how you avoid downtime – never cease your current service until:
The new circuit is installed
It has passed testing
Your internal network migration is complete
This creates a parallel connection.
Step 3: Install the new circuit alongside the old one
Your new provider will:
Run fibre into your premises
Install a new NTE (Network Termination Equipment)
Provide a managed router
Test performance and SLA compliance
Congratulations, you now have two active circuits!
Step 4: Migrate during a controlled change window
During off-peak hours (e.g., 7pm–11pm):
Move your firewall/router gateway to the new line
Update routing rules (e.g., SD-WAN, static IPs, VLANs)
Test VoIP, VPN, CRM, cloud apps
Fail back if needed
Downtime: typically <2 minutes, or zero if using dual-WAN.
Step 5: Add failover for future protection
Many SMEs add:
4G/5G backup (£10–£40/month)
FTTP secondary line (£30–£60/month)
Dual leased lines for mission-critical sites
This ensures continuity even during fibre faults.
Step 6: Cancel your old contract once migration is complete
Once your new line is stable, cease the old circuit!
Please note that early termination charges may apply if you leave mid-contract.
Downtime Risk Comparison
Setup
Expected Downtime
Notes
Parallel circuit + change window
0-2 minutes Best method
Hot failover (FTTP/4G)
0 seconds Instant failover
Switching without parallel circuit
4-48 hours Not recommended
Forced cessation
1-7 days High risk
Costs to Consider When Switching Providers
Cost Type
Typical Amount
Notes
New leased line monthly fee
£139–£350
Based on 100Mb–1Gb
Excess Construction Charges (ECCs)
£0–£3,000
50–60% pay £0
Router or hardware fee
Free–£150
Depends on provider
Early termination fee
Remaining contract
If leaving early
Failover add-ons
£10–£40/month
4G/5G backup
Most providers waive installation fees on 36-month terms.
Can You Keep Your Existing IP Address Range? In most cases, no…IP ranges are assigned per provider. However, you can mitigate disruption by:
Using internal static IPs (unchanged)
Updating external DNS records during the migration window
Using DDNS or rapid DNS TTL adjustments
Using load balancers or SD-WAN
Switching Leased Lines When Moving Office For office moves, leased line installation should begin as soon as the new address is confirmed (ideally 90 days before relocation).
Use temporary:
FTTP
5G routers
Mobile broadband
if fibre installation overlaps the move date.
Key Takeaways
✔ Switching leased line providers without downtime is easy using a parallel circuit.
✔ Installation takes 45–90 days, so order early.
✔ A controlled migration window reduces downtime to under 2 minutes.
✔ Adding failover prevents future outages entirely.
✔ Switching can save UK SMEs £500–£3,000+ per year on contract renewals.
✔ Always cancel the old service after the new line is live and tested.
FAQs 1. Can I switch leased line provider without downtime?
Yes, by installing a parallel leased line before ceasing your current one, downtime can be brought to under 2 minutes or eliminated entirely.
2. How long does it take to switch leased line providers?
Switching usually takes 45–90 days, as the new line must be installed and tested before migration.
3. Do I need to cancel my old leased line before installation?
No, always keep your existing line active until the new one is live and fully migrated.
4. Will switching leased line providers interrupt my VoIP or VPN?
Not if migration is done during a planned change window and the provider configures routing correctly.
5. Are there costs involved in switching?
Possible costs include ECCs (£0–£3,000), hardware, and early termination fees. Monthly pricing depends on speed (typically £139–£350).
6. Can I keep my IP addresses when switching?
Usually not, but good network planning (DNS changes, static internal IPs) minimises impact.
7. What’s the safest way to switch with zero downtime?
Use dual-WAN or hot failover (FTTP/4G/5G) so traffic automatically fails over during the migration.
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Hi, I’m Ally Cox , a senior copywriter and blogger at CompareYourBusinessCosts.co.uk, the UK’s trusted platform for comparing business services.over a decade of experience in the B2B sector, I specialise in simplifying complex topics like leased lines, VoIP, business energy, HR and payroll solutions, accounting software, and EPOS systems .HR, copywriting, and business operations- from clocking-in systems to card machines and office technology .informed, confident decisions when choosing products and services that improve efficiency and save money.