Sound familiar?
- The office stops when the broadband goes down
- Card machines fail every time the router reboots
- Your VoIP phones go silent during an outage
- Openreach says the fault will take days to fix
- You work in a rural area where the line drops in bad weather
- Staff hotspot their phones and the bill shoots up
Key facts
- A dual-WAN router watches the main line and fails over to a backup in seconds
- 4G or 5G backup uses a data SIM in the router or a separate mobile router
- Ofcom's Connected Nations 2025: 5G outdoors from at least one operator covers 97% of the UK
- Coverage by individual network ranges from 64% to 89%, so check each network at your address
- Starlink is a satellite option for rural sites with poor mobile signal
- Openreach's analogue phone network closes by 31 January 2027, so phones depend on broadband too
- Advice and set-up: £45 an hour + VAT; on-site installs quoted
Why a backup line matters more now
Most small offices now run entirely on one internet connection: Microsoft 365, cloud accounting, card payments and, increasingly, the phones. Openreach's parent BT Group plans to retire the old analogue phone network by 31 January 2027, so phone lines are moving to digital VoIP services that need broadband to work. When the line goes, everything goes.
Broadband faults are not always quick to fix. A cut cable or exchange fault can take days. A backup connection does not need to be as fast as your main line, it just needs to keep the essentials running until the main line is back.
How failover works
A dual-WAN router has two internet connections plugged in. It checks the main line constantly, for example by pinging a reliable address, and when the checks fail it moves traffic to the backup within seconds. When the main line recovers it moves back.
- Failover only: the backup sits idle until needed. Simple, and keeps mobile data use low.
- Load balancing: both lines carry traffic all the time. Useful when both are decent, but harder to control on metered data.
- Policy routing: send phones and card machines over the backup first, and keep big downloads on the main line only.
Some ISP routers have a 4G backup built in or available as an add-on. Business routers from firewall and networking vendors give more control. If you already have a firewall we manage, see firewall support.
4G and 5G backup
The most common backup is a mobile data SIM, either in a router with a built-in modem or in a separate 4G or 5G router connected to the main router's second WAN port. Ofcom's Connected Nations 2025 report, published 19 November 2025, says 5G is available outdoors from at least one operator across 97% of the UK, but individual networks range from 64% to 89%. Indoor signal is lower, especially in older stone buildings and industrial units.
So the network matters. We check the coverage checkers of each operator for your postcode, test signal on site where possible and place the router or an external antenna where signal is best, often near a window or high up. A business data SIM with a sensible allowance avoids surprise bills.
Starlink for rural sites
Where mobile signal is weak, Starlink's satellite service is a realistic backup. Ofcom's 2025 report counted over 110,000 Starlink subscribers in the UK. It needs a dish with a clear view of the sky and power, and it plugs into a router's WAN port like any other connection. Starlink sells business plans in the UK; plan names and prices change, so check Starlink's own site. Latency is higher than fibre but fine for email, web and most VoIP calls.
What to keep running in an outage
- Card payments: make sure terminals use the office network or their own SIM. Many have a built-in SIM fallback already.
- Phones: VoIP systems usually re-register on the backup line within a minute or two. Set mobile apps or call forwarding as a second fallback. See VoIP phone support.
- Power: a small UPS for the router, switch and backup modem keeps the connection up through short power cuts.
- Alerts: get an email or text when failover happens, so you report the fault straight away instead of discovering it a week later.
How dijitul helps, and pricing
We look at your current connection and router, check mobile coverage for your address, recommend a backup option and configure the failover rules and alerts. Most of this is done remotely at £45 an hour + VAT. If a new router, external antenna or dish needs fitting on site, we tell you upfront and quote it. Ongoing router and network support fits within our monthly plans. Related: broadband and router support and network support.
Frequently asked questions
What is broadband failover?
A second internet connection, usually 4G, 5G or satellite, with a router that switches to it automatically when your main broadband fails. dijitul configures the router so the switch happens in seconds and you get an alert.
Is 4G or 5G good enough as a backup?
For most small offices, yes, for email, Microsoft 365, card payments and phone calls. Signal at your building is the deciding factor. Ofcom reports 5G outdoors across 97% of the UK from at least one network, but each network's coverage differs.
Can Starlink be used as a backup line?
Yes. Starlink plugs into a dual-WAN router like any other connection. It suits rural sites with poor mobile signal, as long as the dish has a clear view of the sky. Check Starlink's site for current UK plans.
Will my VoIP phones keep working on the backup?
Usually, yes. Phones re-register over the backup connection, often within a minute or two. dijitul tests this during set-up and can prioritise voice traffic on the backup line so calls stay clear.
Do I need a new router for failover?
Not always. Some ISP and business routers have a second WAN port or a 4G add-on. If yours does not, dijitul recommends a suitable dual-WAN router and quotes any on-site fitting upfront.
How much does it cost to set up?
dijitul charges £45 an hour + VAT for advice and remote configuration. The backup SIM or Starlink plan is paid to the provider. Any on-site installation is quoted before work starts.
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