Buying a VoIP phone system: five lessons first-time buyers learn the hard way

Lesson 1: your network is the phone system

Every disappointing VoIP install traces back to the same root cause: the buyer evaluated phones and features, but never evaluated the internet line the calls would ride on.

VoIP turns every call into a real-time stream of small data packets. A single call on the standard G.711 codec needs roughly 100 kbps in each direction once you include packet overhead, and the one-way delay needs to stay under about 150 milliseconds for the conversation to feel natural. Those numbers sound trivial against a 100 Mbps fibre line, and they are, until five people are on calls while someone uploads a backup and a video meeting saturates the same connection.

The fix is not more bandwidth. It is prioritisation: a router that puts voice traffic ahead of everything else (quality of service, or QoS), and an honest count of how many simultaneous calls your business actually makes at its busiest hour. If your connection is genuinely constrained, providers can run the G.729 codec, which compresses each call to a fraction of the bandwidth at a small cost in audio richness.

Our VoIP device setup checklist covers the network groundwork in detail, and if calls do degrade after install, the diagnostic path in when a PC softphone goes wrong applies to desk phones too.

Lesson 2: the package structure decides your bill, not the rate

First-time buyers compare per-minute rates. Experienced buyers compare billing structures, because that is where the real money moves.

South African VoIP pricing comes in a handful of shapes, and the right one depends on your call profile rather than the headline rate:

• Capped vs uncapped: capped bundles are cheaper when your call volume is predictable; uncapped suits businesses where a busy month should not produce a surprise invoice.
• Per-second billing: widely available in SA and worth insisting on. A business that makes many short calls pays materially less per-second than per-minute, because a 65-second call bills as 65 seconds, not two minutes.
• Prepaid vs postpaid: prepaid gives you a hard cost ceiling and is a useful discipline for a first deployment; postpaid is more convenient once your usage pattern is known.
• Contract vs month-to-month: contracts buy discounts and sometimes hardware, but a month-to-month start lets you test a provider against reality before committing. No-contract options exist across the SA market.

For a sense of where entry pricing sits across the market, see our regularly verified cheapest VoIP providers in South Africa roundup.

Lesson 3: you can keep your number, so port it properly

The single most expensive mistake a first-time buyer can make costs nothing to avoid: cancelling the old line before the number has been ported.

South African businesses have the regulatory right to move a geographic number between providers. The new provider runs the porting process for you, but the sequencing is on you: the old service must stay active until the port completes. Cancel first and the number can be lost back into the donor operator’s pool, taking years of business cards, signage and customer memory with it.

The full process, documentation pack and the common reasons ports get rejected are covered in our guide to number porting for VoIP phone systems.

Lesson 4: security is your job too

A VoIP system is a service reachable over the internet, and the classic attack is depressingly practical: criminals hijack an account and pump premium-rate calls through it overnight.

Toll fraud is preventable with basic discipline, and a good provider will help, but the buyer has to ask. Before going live, confirm these four controls are in place:

Lesson 5: adoption beats features

Buyers agonise over feature lists, then discover the real differentiator is whether the team actually uses the system confidently.

Modern VoIP platforms all do the core things: call transfer, voicemail-to-email, mobile apps, call recording. The gap between a good deployment and a frustrating one is rarely a missing feature. It is a receptionist who never learned to transfer calls, a salesperson whose softphone microphone was never set up, a voicemail greeting still reading out the default message three months in.

Two practical moves close that gap. First, decide deliberately between desk phones and softphones per role rather than buying handsets for everyone by default; desk-bound, call-heavy roles justify hardware, while mobile and hybrid staff are usually better served by the app. Second, book the provider’s onboarding session and make the whole team attend it. It is usually included in the price and almost always skipped.

Keep reading