Published: 13 October 2026 | By AOLC
If your business runs on a VoIP phone system, load shedding raises a question every South African business owner has asked at some point: "Will my phones still work when the power goes out?"
The short answer is: it depends on how your system is set up. VoIP done right is actually more resilient during load shedding than a traditional landline or on-premises PBX. VoIP done poorly goes dead the moment power cuts — and stays dead until someone manually intervenes. This guide explains the difference, what equipment you need, and how to build a failover plan that keeps your business reachable no matter what Eskom throws at you.
A traditional on-premises PBX goes completely dark when power fails. With a cloud-hosted VoIP system and failover routing configured in advance, your staff can answer business calls on their mobile when load shedding hits — with no IT intervention needed in the moment.
To understand how load shedding affects VoIP, you need to understand what VoIP actually requires to work:
This is the core load shedding problem: the phones themselves might be fine, but if your network equipment loses power, they cannot reach the outside world. This is true whether you use physical IP desk phones, softphones on a laptop, or a mobile app — they all depend on your internet connection.
of runtime a properly sized UPS provides for your router and switch during load shedding — enough to cover most scheduled outages in South Africa.
The biggest factor in load shedding resilience is where your phone system lives — in the cloud, or in a box on your premises.
A traditional PBX (Private Branch Exchange) is a physical server that sits in your server room and handles all your call routing. When load shedding hits and your generator or UPS cannot keep it running, the PBX goes offline — and with it, every extension in the building. Incoming calls to your office numbers either ring out or go to voicemail, with no automatic failover to mobile. Your staff cannot make or receive calls until power is restored and the system reboots.
This is the load shedding worst-case: a hardware box, in your building, that must stay powered and connected to keep your business reachable.
With a cloud-hosted VoIP system, your phone system lives in a datacentre — not your building. The call routing logic, voicemail, IVR menus, and call recording all run in the cloud, 24/7, on infrastructure with its own redundant power. Load shedding at your office does not affect the phone system itself.
What it does affect is your last-mile connection: the router at your premises that links you to the cloud. If that loses power, your desk phones and office laptops cannot reach the VoIP platform. But your staff's mobile phones can — because they connect over 4G/LTE, independently of your office internet.
Tip
Install the VoIP provider's mobile app on every staff member's smartphone before load shedding season. If the office internet goes down, calls automatically ring through to the app over mobile data — no IT intervention needed in the moment.
A well-designed VoIP load shedding plan has three layers, each one a fallback for the layer above it:
This is your first line of defence. A UPS (Uninterruptible Power Supply) sized for your router, switch, and any fibre ONT (the box your ISP installs) costs between R1,500 and R3,500 and provides two to four hours of runtime — enough to cover most scheduled load shedding stages in South Africa. This keeps your office internet alive during an outage, which means your desk phones and laptops keep working as normal. Staff do not need to switch to anything; the transition is seamless.
Key equipment to put on the UPS:
Do not put printers, monitors, or general office equipment on the UPS. You want the battery focused entirely on the devices that keep your internet and phones alive.
If the outage exceeds your UPS runtime, or if the battery has not been tested recently and fails early, you need a fallback that does not depend on your office internet at all. Most modern cloud VoIP platforms include a mobile app that connects via 4G/LTE. When the office internet drops, incoming calls to your business number can be configured to ring the app — so your staff answer on their phone, and the caller has no idea anything is wrong.
This requires two things to be set up in advance:
mobile failover keeps your business phone lines open even when the office internet is completely down — staff answer on their smartphone, callers hear your normal greeting.
For businesses where missing a single call is genuinely costly — a medical practice, a sales team, a helpdesk — a third layer adds overflow routing at the platform level. If all devices on a queue or hunt group are unreachable (because the whole team is in an area hit by load shedding simultaneously), calls can overflow to a secondary number, a voicemail-to-email inbox, or a WhatsApp Business line. This is configured in your VoIP platform's call flow settings and requires no additional hardware.
Understanding the failure modes helps you prepare. Here is a realistic breakdown:
| Scenario | Impact on VoIP | Mitigation |
|---|---|---|
| Load shedding, network gear on UPS | None — phones work normally | Test UPS battery quarterly |
| Load shedding exceeds UPS runtime | Desk phones and laptops go offline | Mobile app failover on 4G |
| ISP fibre cut or cable theft | Office internet down regardless of power | Mobile failover; LTE backup router |
| On-premises PBX, no backup power | Complete outage — no calls in or out | Add a UPS (buys 2–4 h runtime) or migrate to cloud-hosted VoIP |
| Cloud VoIP, staff mobile data off | Mobile app cannot receive calls | Enable data on staff mobiles; use 4G router for laptop softphones |
A UPS keeps your office internet alive during load shedding. But if your fibre line goes down for another reason — cable theft, an ISP fault, or a prolonged outage — your UPS will not help. For businesses where internet and phone availability is business-critical, an LTE backup router (also called a failover router) provides a secondary data path that kicks in automatically when the primary fibre line drops.
Entry-level LTE failover routers start at around R2,000 to R4,000, with a monthly SIM data cost depending on expected usage. For a business that handles 50 calls a day, a 10 GB LTE SIM is typically enough to cover a day of failover at normal call volumes. High-call-volume businesses (call centres, busy reception desks) should size the SIM larger and test their consumption before relying on it.
Tip
Test your LTE failover before you need it. Unplug the fibre from your main router and confirm that VoIP calls still connect within 60 seconds. Many failover routers have a switchover delay that can be tuned — get this right during a planned test, not during a live outage.
Before the next scheduled outage, work through this checklist to confirm your VoIP system is properly protected:
Load shedding is a permanent feature of doing business in South Africa, but it does not have to mean missed calls and lost customers. A cloud-hosted VoIP system with a basic UPS on your network gear, mobile app failover configured on every extension, and a tested LTE backup is genuinely more resilient than a traditional landline or on-premises PBX — at a fraction of the cost of keeping a generator running just for the phones.
The businesses that lose calls during load shedding are those that assumed their system would cope without ever testing it. The ones that stay reachable are the ones that built the plan before the power went out. If you are not sure whether your current setup will survive the next outage, now is the time to find out.
AOLC supplies, installs, and supports cloud-hosted VoIP for businesses across South Africa — including a load shedding failover plan as standard. Get a no-obligation quote.
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