VoIP & Communications
VoIP and business continuity: keeping the phones working when the office cannot open
How hosted VoIP keeps a UK business answering calls during office closures, power cuts, broadband faults and bad weather, and what to set up before you need it.
By Dig IT SolutionsUpdated 8 September 20266 min read
Short answer
Hosted VoIP supports business continuity because the phone system lives in the provider's data centres, not in your building. If the office is closed, flooded or without power, staff answer the same numbers from the mobile or desktop app anywhere with internet. Divert rules, a 4G backup and a tested plan turn that capability into calls actually answered.
Most continuity planning focuses on data and servers. Yet the first thing customers notice when a business is disrupted is that nobody answers the phone. A traditional PBX sits in a cabinet in the office and stops working when the building floods, the power fails or the broadband goes. A hosted VoIP business phone system removes that single point of failure, but only if it has been set up with continuity in mind. This article explains what VoIP gives you during an office closure, what it does not, and the handful of things to configure before you need them.
Why the phone system is a continuity problem
When an office cannot open, work carries on somewhere else, but customers still ring the number on the website. With a PBX in the building, the options are a manual divert set up by the line provider (slow, and only to one number) or nothing. Calls ring out, enquiries go to competitors and existing clients assume the worst. Suppliers cannot reach accounts. Managers cannot coordinate staff.
The wider business continuity plan should treat "can customers reach us" as a critical function with its own recovery target, in the same way as email and the main line-of-business system.
What hosted VoIP changes
With a hosted platform, the phone system is a service in the provider's data centres. The office is just one place people log in from. During a closure:
- Staff open the mobile or desktop app from home and are on the same extensions, queues and directory.
- The main number, DDIs and auto-attendant carry on unchanged. Callers dial what they always dial, and nothing on the website, the van or the invoice needs changing.
- Transfers between colleagues work whether they are at home, in another branch or on the road.
- Voicemail-to-email and presence keep working, so nothing is lost in a personal mobile.
- Administrators change routing and greetings from a browser, not from a cabinet in the closed building.
For a multi-site business, calls to a closed branch can divert to another one in minutes. Our guide to VoIP for multi-site businesses covers that routing in more detail.
Scenarios and what happens in each
| Disruption | Traditional PBX | Hosted VoIP, set up properly |
|---|---|---|
| Severe weather, staff cannot travel | Phones unanswered or single divert | Staff answer from home on the app, no change for callers |
| Power cut at the office | Phones dead | Desk phones on UPS carry on, otherwise auto-divert to mobiles |
| Broadband fault at the office | Phones fine, everything else down | 4G or 5G backup keeps desk phones live, or divert to mobiles |
| Flood, fire, building closed for weeks | Engineer visit to divert lines, weeks to re-establish | Work from home or temporary space immediately, same numbers |
| Planned refurbishment or office move | Line transfers, downtime | Log in from the new location, nothing to move |
| Cyber incident on the office network | Depends on PBX exposure | Phones isolated in the cloud, apps on mobile data still work |
A worked example: two days without the office
A 30-person accountancy practice in Hertford loses its office to a burst pipe on a Tuesday morning in January, during self-assessment season. The building is closed for two days while the water is cleared.
By 9:15 the practice manager has switched the auto-attendant to the pre-recorded "we are working remotely" greeting from her phone. Staff open the 8x8 app at home and are on the same extensions. Reception answers the main number from her kitchen table, sees on the Teams presence panel which partners are free and transfers calls as usual. Two clients ring the direct lines of fee earners who are out fetching laptops from cars, and those calls fall through to voicemail-to-email and are returned within the hour.
Nobody rings a personal mobile. The call log for both days is complete. The one problem, an associate with poor home Wi-Fi whose calls kept breaking up, is fixed by switching the app to mobile data. On Thursday the office reopens and the greeting is switched back. Clients who rang during the closure did not know it had happened.
The same event with a PBX in the flooded comms room would have meant two days of unanswered calls at the busiest point of the year.
What VoIP does not do on its own
VoIP gives you capability, not a plan. Three things trip businesses up:
Power at the office. VoIP desk phones need the switch, router and broadband equipment to be up. A small UPS on the comms cabinet keeps them running through short cuts. For anything longer, staff move to the app.
Connectivity at the office. A 4G or 5G backup on the router keeps the office working through a broadband fault, which is the most common disruption of all. Without one, calls can still divert to mobiles, but PCs and desk phones will be off. The specifics of failover and quality of service are in is VoIP reliable for business calls.
Connectivity at home. Staff who answer calls from home need a headset, a decent connection and a quiet space. Test call quality from home during onboarding, not during the first snow day.
Set it up before you need it
A short list, most of which takes an afternoon:
- Install the app for everyone. Desktop and mobile, logged in and tested, before any incident.
- Write the divert rules. If desk phones go offline, ring the mobile app. If nobody answers in 30 seconds, voicemail-to-email to a monitored inbox.
- Record closure greetings in advance. Short closure, severe weather, longer incident. Switch between them from the portal.
- Add a 4G or 5G backup to the office router and a UPS to the cabinet.
- Decide who can change routing and make sure two people have admin access and know how.
- Keep a printed contact list of staff mobiles, the VoIP provider's support line and your IT provider, somewhere that does not depend on the office.
- Test twice a year. Pull the broadband, ring the main number, transfer a call between two home workers, switch the greeting, and time it.
Each of these is a small job. Together they are the difference between a phone system that could theoretically keep working and one that does. The businesses that struggle during closures are rarely missing the technology. They are missing the two-minute admin change nobody knew how to make.
Put the result in the IT disaster recovery plan alongside the server and data recovery steps, so telephony is restored in the same exercise rather than remembered afterwards.
Security during disruption
Continuity should not loosen security. Staff logging in from home should use strong passwords or single sign-on and multi-factor authentication on the VoIP platform, international dialling should stay restricted, and admin rights should stay with the two named people. Fraudsters watch for businesses in disarray, and an open phone platform is a target for toll fraud, where compromised accounts are used to dial premium-rate numbers overnight and the business finds out from the invoice.
It is also worth agreeing in advance what staff may say to callers during an incident. A short line, such as "we are working remotely today and can help as normal", is better than improvised explanations that alarm clients.
What to do next
If your phone system would not survive a day with the office closed, that is a gap worth closing before winter. Dig IT deploys 8x8 with divert rules, backup connectivity and a tested failover as standard. Talk to an engineer about how your calls would be handled tomorrow if the office could not open.