Power cuts and network interruptions can affect everyday communication, leaving UK households uncertain about whether their landline call blockers will continue functioning. Since scammers often take advantage of confusion during service issues, it’s important to understand how these devices operate during outages.
This blog explains how landline call blockers work during power or service interruptions and what households can do to stay protected.
Do Landline Call Blockers Continue Working During Power Cuts In The UK?
Whether a landline call blocker works during a power cut depends on the type of landline service the household uses. Traditional PSTN (Public Switched Telephone Network) lines typically continue operating during outages, while digital and broadband-based phone services depend on electricity.
Here’s how call blockers perform in common UK scenarios:
- Traditional PSTN landlines: These lines carry their own electrical charge, allowing both the phone and the landline call blocker to stay operational during power failures.
- Digital Voice, fibre, and broadband phone services: These require power and an internet connection. If the router or modem loses power, the entire phone service—including the call blocker—stops functioning temporarily.
- Battery backup solutions: Households using Digital Voice or broadband phones can connect their routers to battery backup units to maintain service during short outages.
Ofcom’s 2025 Communications Report notes that as the UK transitions to all-IP networks, more households are relying on broadband-based phone services making backup power increasingly important.
Summary: Landline call blockers continue working during power cuts on PSTN lines or any system with battery backup.
How Do Service Interruptions Affect Landline Call Blocker Performance?
Service interruptions—such as broadband outages, network faults, or damaged lines—affect a call blocker’s ability to filter calls based on whether the line itself is active.
Key scenarios include:
- PSTN line interruptions: If the traditional network is down, no calls come through. The call blocker remains connected but has no calls to process.
- Digital Voice or broadband faults: If the internet drops, phone service halts. Once the network is restored, the call blocker resumes normal filtering instantly.
- Caller ID disruptions: During partial outages, caller ID may fail to display. Call blockers may still block known numbers but may struggle to filter new unknown callers without caller ID data.
- Post-outage scam spikes: After storms or service issues, scammers often impersonate energy providers, councils, or broadband companies. A call blocker becomes especially valuable during these periods.
Summary: Service interruptions temporarily pause phone service, but landline call blockers return to full function once service resumes.
How Can UK Households Ensure Their Call Blockers Stay Effective During Outages?
With the UK gradually moving toward all-digital phone lines, households can take proactive steps to keep landline call blockers functional during outages or service disruptions.
Useful recommendations include:
- Use a battery backup for routers: This helps maintain phone and call-blocker functionality during short power cuts.
- Understand your line type: PSTN lines offer the most reliability during outages until the national switchover completes.
- Check that connections are secure: Proper installation prevents issues after power is restored.
- Update blocklists regularly: After outages, scammers often increase activity—updating blocklists helps keep protection strong.
- Test phone equipment after service returns: Ensures the call blocker resumes filtering accurately.
For elderly residents or vulnerable households, these steps help maintain safety and minimise disruption during emergencies.
Summary: Backup power, proper setup, and post-outage checks help UK households keep their landline call blockers functioning reliably.
Conclusion
Landline call blockers can continue working during power cuts or service interruptions, especially when connected to PSTN lines or backup-powered digital systems. By understanding how these devices behave during outages, households can stay protected even in unpredictable situations. To keep your home communication safe, explore our range of CPR Call Blockers.
FAQ
Q: Do landline call blockers work during power cuts?
A: Yes, they work on PSTN lines and remain functional on digital phone systems with battery backup.
Q: Will the call blocker work if the broadband is down?
A: Not on Digital Voice or broadband systems—the phone service must be active. On PSTN lines, it works normally.
Q: Do scammers target households after service outages?
A: Yes. Scam activity often increases after disruptions, making call blockers very useful.
Q: Should I use a backup battery with my broadband router?
A: Yes. It helps maintain communication and call-blocker functionality during short outages.
