SureTel
Resource · Getting started
What is VoIP?
A plain-English explainer of business VoIP for South African buyers — what it is, how it works, and where it fits.
Educational resource · Not a quote · Licensed South African ISP · ICASA licence 0009/CECS/AUG/09
Answer first
VoIP, in one paragraph
VoIP stands for Voice over IP — business phone calls carried as data over an internet connection instead of over analogue or ISDN lines. A VoIP "extension" is a software login, so the same number rings a desk phone, a laptop or a mobile app. Whether VoIP fits comes down to your call flow, your numbers, and the connection at each site.
- Calls carried as data over the internet, not over analogue lines
- An extension is a login — desk phone, softphone or mobile app
- VoIP is the calling layer; Cloud PBX is the phone system around it
- Existing numbers can usually be ported across
- Fit depends on your call flow, numbers and connection
Problems VoIP solves
The buyer problems VoIP is actually a good answer to
Calls drop or sound rough on a traditional line and we can't see why.
VoIP runs over a managed internet connection — when scoped properly, voice quality is consistent and measurable.
We can't add a new extension without a site visit or new cabling.
VoIP extensions are provisioned in software; adding a user does not need a cable run.
Staff work from multiple sites or from home and the phone system can't follow them.
A VoIP extension is a login — the same number rings the desk phone, the laptop and the mobile app.
We pay for capacity we don't use because the old PBX is sized for peak.
VoIP capacity scales with users and concurrent calls, not with a fixed hardware ceiling.
Our number is on a landline and we're worried about losing it if we change provider.
Numbers can be ported to a VoIP provider as a one-off project — your number stays the same.
We don't know whether VoIP will actually work on the connection we already have.
Whether VoIP fits depends on the connection at your site — that's a feasibility question we can scope.
Where VoIP fits
VoIP, Cloud PBX, SIP trunking and onsite PBX — the picture
VoIP is the underlying calling layer. The broader phone system around it is usually a Cloud PBX, or VoIP can plug into an existing onsite PBX through a SIP trunk. What sits around it depends on whether you want a new hosted phone system, or to keep an existing one.
New hosted system
A Cloud PBX hosts the phone system in the cloud and uses VoIP for calls. New deployments most often go this way.
Cloud PBX →Existing PBX, modern lines
A SIP trunk replaces analogue/ISDN lines on an existing PBX. The PBX stays; only the lines change to VoIP.
SIP trunking →Call-handling teams
Sales and support teams running queues, dialling or supervisor reporting usually layer a dialler on top of VoIP.
Hosted VICIdial →For SureTel's VoIP service specifically, see /services/voip.
Typical scenarios
What VoIP looks like for real teams
A small office on fibre
Six to twenty users on desk phones and softphones, one main number, an after-hours greeting and basic call routing. VoIP suits this well; the fibre line carries voice and data together.
A team split across sites and home
Users in head office, a branch and a few permanent home-workers. Each person has one extension that rings on whichever device they're using, with a single shared business number.
A business keeping its existing PBX
An existing PBX is in working order but the analogue lines are being retired. SIP trunking replaces the lines without replacing the phone system — see /services/sip-trunking.
A call-handling team
A sales or support team that needs queues, supervisor visibility and shared inboxes. This usually pairs VoIP with a Cloud PBX or a dialler — see /services/cloud-pbx or /services/hosted-vicidial.
Terms compared
The VoIP vocabulary, in plain English
The terms you'll see across VoIP quotes and articles, and how they relate to each other.
| Term | Plain English | How it relates to VoIP |
|---|---|---|
| VoIP | Voice over IP — phone calls carried as data over an internet connection. | The underlying technology this article explains. Everything below is either part of VoIP or sits next to it. |
| SIP | Session Initiation Protocol — the signalling standard most business VoIP uses to set up and end calls. | Most modern VoIP services are 'SIP-based'. SIP is how, VoIP is what. |
| SIP trunk | A voice connection between an existing PBX and a VoIP provider, in place of analogue lines. | Lets a business keep its existing PBX hardware and use VoIP for outgoing/incoming calls. |
| Cloud PBX | A hosted business phone system — the PBX itself runs in the provider's cloud, not in your server room. | Cloud PBX uses VoIP for calls but adds the phone-system features (extensions, IVR, queues, voicemail). |
| Onsite PBX | A traditional on-premises phone system, with hardware in your building. | Can still use VoIP via a SIP trunk; replaced by Cloud PBX in many new deployments. |
| Extension | A user or device on the phone system — a desk phone, a softphone or a mobile app. | On VoIP, an extension is a software login, not a physical port on a board. |
| Concurrent calls | How many calls can be active at the same time across all extensions. | A separate dimension from user count — quoted alongside extensions on most VoIP services. |
| DID / number | A telephone number you publish to customers — geographic, national or toll-free. | Numbers are usually billed separately from extensions and can be ported in or out. |
How a VoIP call gets from A to B
The call path, in five steps
- Step 1
You speak
Desk phone, softphone or mobile app captures audio.
- Step 2
Encoded as data
Audio is encoded into IP packets — voice becomes data.
- Step 3
Over your connection
Packets travel over your internet connection to the provider.
- Step 4
Routed by the provider
The platform routes the call to its destination network.
- Step 5
Reassembled on the other side
Packets are decoded back into audio at the far end.
Before you move
What to sort out before you switch to VoIP
Check the connection at every site
VoIP quality depends on the internet connection it runs over. Most business fibre is fine; check ahead of time, not after go-live.
Decide what happens to your numbers
Existing numbers can be ported. Plan this as a one-off project with its own lead time, separate from the service price.
List the call flows you actually use
Hours, after-hours, IVR menus, departments, queues — write them down before scoping. They translate directly into the new setup.
Decide handsets vs softphones
Many teams run on softphones (desktop and mobile apps); others want IP desk phones. Both work — it's a per-user decision.
Plan the change-over
Provisioning, training and a clean cut-over date matter as much as the technology. Treat it like a small project, not a swap.
Pricing signpost
How much does VoIP cost?
How VoIP pricing actually works
Users, calls, numbers, hardware, setup and support are billed as separate components. The pricing guide explains how to read a VoIP quote without the marketing gloss.
Read the VoIP pricing guide →SureTel's current public prices
Current SureTel public starting prices for business VoIP, in South African Rand, excl. VAT.
View VoIP pricing →All amounts referenced are excl. VAT. This page is a definitional explainer, not a quote or rate card.
Why SureTel
A South African business communications partner
- Licensed South African ISP — ICASA licence 0009/CECS/AUG/09
- Operating since 2010, with hundreds of satisfied customers
- Point of presence at NTT Johannesburg (JOH1) data centre
- Business voice and connectivity under one provider
- Practical scoping — feasibility first, quote second
How to use this article
From "what is VoIP?" to a real quote
Read the explainer
Understand what VoIP is and where it fits before talking to a provider.
Sense-check pricing
See how business VoIP is actually priced in South Africa before requesting a quote.
Read the service page
When evaluating SureTel specifically, the commercial detail lives on the VoIP service page.
Check current prices
Current SureTel public starting prices for VoIP, excl. VAT.
Request a quote
When you're ready, request a quote scoped to your team and call profile.
Signposts for each step live in §4 (service), §9 (pricing) and §13 (quote).
VoIP FAQs
Frequently asked questions about VoIP
What is VoIP in simple terms?
VoIP stands for Voice over IP. It means your phone calls are carried as data over an internet connection instead of over traditional analogue or ISDN lines. To the person on the other end, a VoIP call sounds like any other phone call.
Is VoIP the same as a Cloud PBX?
No. VoIP is the calling technology; a Cloud PBX is a hosted business phone system. A Cloud PBX uses VoIP for calls but adds phone-system features like extensions, IVRs and queues. You can also use VoIP with an existing onsite PBX via a SIP trunk.
Will VoIP work on my existing internet connection?
Often yes, but it depends on the connection at your site — its reliability, available bandwidth and how it's being used. This is a feasibility question we scope before quoting; we don't promise quality without checking the line.
Can I keep my existing phone number if I switch to VoIP?
Usually yes. Existing numbers can be ported to a VoIP provider as a one-off project with its own lead time. See /resources/number-porting-south-africa for how porting actually works in South Africa.
How much does VoIP cost?
Business VoIP cost depends on users, call mix, numbers, hardware, setup and support. This explainer is not the pricing page — for how VoIP pricing actually works, see /resources/voip-pricing-south-africa; for SureTel's current public starting prices, see /pricing/voip.
Do I need new desk phones for VoIP?
Not necessarily. Many teams use softphones (desktop and mobile apps). IP desk phones are an additional one-off cost where they're genuinely needed.
What happens if the internet goes down?
VoIP needs a working internet connection. Sites that need voice during an outage typically pair their primary connection with an LTE/5G backup that's configured to fail over. See /services/lte-5g-backup.
Is VoIP secure?
A properly configured business VoIP service uses encrypted signalling and call audio between the handset/softphone and the provider. Security is part of how a service is scoped and deployed — not a default tick-box.
Is VoIP a good fit for small businesses?
Often, yes. VoIP scales with users rather than with hardware ports, and a small team can start with softphones and add extensions as they grow. Whether it's the right call depends on your connection, your call flow and your numbers — all of which we'd scope before quoting.
Next step
Ready to look at VoIP for your business?
When you're moving from "what is it?" to "is it right for us?", the SureTel VoIP service page covers the commercial detail, and the pricing page covers current starting prices.
Educational resource · Not a quote · All amounts referenced excl. VAT