Yes — modern VoIP on a decent business broadband connection is more reliable than the copper landline it's replacing. But the failure modes are different, and if you plug it into a consumer broadband line with no fallback, you'll have a bad time. Here's the honest picture.
Why VoIP is more reliable than landlines now
Openreach is switching off the PSTN (traditional copper phone network) in January 2027. Every UK business line is moving to IP one way or another — the question is whether you plan the transition or get moved on your ISP's timeline.
Cloud-hosted VoIP platforms typically run on redundant data centres with 99.99%+ platform uptime. Your calls survive a data centre failure. Old on-premise PBXs did not survive a lightning strike or a power cut.
The failure modes to plan for
Broadband outage. If your internet dies, your calls die with it — unless you've configured automatic call forwarding to mobile, which every serious VoIP platform supports.
Power cut. Old analogue phones drew power from the line itself. VoIP handsets need mains power. A UPS on your router and switch is cheap insurance.
Insufficient upload bandwidth. Rule of thumb: 100 Kbps up per concurrent call using G.711, ~30 Kbps using Opus. A 10-person office needs 1 Mbps of headroom minimum — trivial on modern fibre, tight on old ADSL.
How to make VoIP bulletproof
Pair VoIP with business broadband (not home) — you get traffic prioritisation and an SLA.
Enable QoS on your router so voice packets get priority over Netflix and Windows updates.
Configure failover routing on your VoIP account: if the office line drops, calls automatically forward to mobiles or a secondary site.
For revenue-critical phone lines (sales teams, contact centres), add a 4G/5G backup router that kicks in automatically when the main line fails. Under £30/month.
Frequently asked questions
Is VoIP as reliable as a landline?
On business broadband, yes — typically 99.9%+ uptime, which matches or beats what most UK landlines deliver in practice. The failure modes differ: VoIP depends on your internet, so plan for outages.
What happens to VoIP if the internet goes down?
Calls in progress drop. Incoming calls can be set to auto-forward to a mobile or another site — every modern VoIP provider supports this out of the box.
How much bandwidth does VoIP use?
About 100 Kbps up per concurrent call on G.711, or 30 Kbps on Opus. A 10-person office comfortably runs on any fibre broadband.
Is VoIP secure?
Yes when configured properly — TLS for signalling, SRTP for media, strong SIP passwords, and IP-restricted trunks. The risk is misconfiguration, not the technology.
When is the UK PSTN switch-off?
January 2027. Openreach is retiring the copper phone network — every UK business phone line is moving to IP. Better to migrate on your schedule than your provider's.