AI voice • How-to

How to add AI to the phone system you already have

You do not need a new phone system to get an AI receptionist. There are four ways to put AI on the line you already run, and the right one depends on what that system is.

Last verified 2 October 2026 By Mechelle Gindra, Editorial Lead 8 min read

4ways to add AI without replacing your phone system

R0setup on the self-setup AI receptionist plans we track

8 of 8AI voice providers in our record hand calls to a person

0SA mobile operators with network AI calling live yet

The short answer

How do I add AI to my phone system?

Add a layer rather than replacing anything. On 3CX or Yeastar, switch on the vendor’s AI receptionist add-on. On any other system or number, forward calls to an AI receptionist service and keep your number. Technical teams can connect a self-build platform over a SIP trunk. Start with missed and after-hours calls.

routes to AI that keep your current phone system and number

of free AI time with Yeastar’s AI Receptionist before a top-up

maximum length of a single AI call on 3CX’s AI Receptionist

or fewer of calls a live AI receptionist we studied fully resolved

An ordinary desk phone on an office desk with a laptop behind it showing an abstract call-flow screen — The phone on the desk can stay. AI is added in front of it, inside it or beside it.

Which way of adding AI fits your phone system?

It depends on one question: what do you run today?

An AI voice agent needs to sit somewhere in the path of a call: inside your phone system, in front of your number, or on a separate line your system can reach. Where it can sit depends on what you already have. A business on 3CX has an option a business on a Telkom landline does not, and the reverse is also true.

This guide is for businesses keeping their current system. If you are replacing it anyway, read how to choose a future-ready phone system instead. If you are new to the idea, what an AI receptionist is covers the basics.

Find your route

Route 1: does your phone system have an AI add-on?

If you run 3CX or Yeastar, yes, and it is the most direct option.

Both platforms now sell an AI receptionist that lives inside the phone system itself. The AI answers on the same lines, uses the same extensions and transfers calls to people the way any other call is transferred. Nothing sits in front of your number.

3CX AI Receptionist

AI Edition licence

Entry price€550/yr, 8 calls
AI engineYour OpenAI account
Longest AI call3 minutes
ChannelVoice only

Yeastar AI Receptionist

Add-on subscription

Runs onP-Series Software Edition
Free minutes60, once-off
After thatTop-up or 200 min/month
Add-on priceNot published

3CX includes its AI Receptionist in the 3CX AI Edition, which is priced at €550 a year at the 8-simultaneous-call tier. It greets callers, collects details, routes and screens calls and hands complex ones to a person. It is powered by OpenAI: the administrator connects the system to an OpenAI account, so the AI usage is a second bill. A single AI call is capped at three minutes, which suits greeting and routing better than long conversations. More in our 3CX review.

Yeastar‘s AI Receptionist is a subscription add-on for the P-Series Software Edition, from firmware 83.24.0.30. It detects the caller’s language and answers in it, and it can be reached on a direct number or from your existing inbound routes and IVR. It comes with 60 free minutes, then a once-off top-up or a 200-minute monthly pack. Yeastar does not publish the add-on prices; your reseller sets them. Our Yeastar AI Receptionist teardown goes further.

On a hosted 3CX or Yeastar, the switch is usually your provider’s. Most South African businesses rent these systems through a reseller who controls the licence, firmware and settings. Ask them whether the AI add-on is available on your version and what they charge for it before you plan around it.

Route 2: can you add AI by forwarding calls?

Yes, and it works with almost any phone system, because the AI sits in front of your number rather than inside your system.

This is the route most businesses can take today. You keep your number and your phone system, and set some or all calls to forward to an AI receptionist service. The AI answers, handles what it can and transfers the rest back to your staff. There is no porting and no new hardware.

AiSky says it works with an existing Telkom, Vodacom, MTN, Cell C or Rain number, by forwarding or SIP, with no setup fee. SME Advantage works by forwarding only; it does not port numbers. BizAI‘s Voice Valet is an AI receptionist add-on at R999 a month excluding VAT, with 100 AI-answered minutes and then R3.50 a minute, added to one of its Smart CRM plans from R599.

You also choose which calls the AI gets. Most phone systems and networks can forward on four conditions:

When nobody answersThe AI picks up after a set number of rings. The best place to start: it only takes calls you would otherwise miss.

After hoursCalls outside office hours go to the AI. Often the biggest win for small teams.

When the line is busyThe AI catches overflow at your busiest times instead of a second caller hearing an engaged tone.

All callsThe AI answers first and transfers. Only do this once you have measured how well it resolves calls like yours.

Ask how forwarded calls are billed. On many lines a forwarded call is charged as an outgoing call from your number to the AI service’s number, on top of the AI plan. Check with your phone provider before you forward all calls, and see what an AI voice agent really costs for the bills that arrive separately.

Starting with missed and after-hours calls also changes the job from replacing your receptionist to helping them, which is the approach we argue for in free up your receptionist, don’t replace them.

You do not replace a phone system to add AI. You decide which calls it answers first.

WhichVoIP editorial view

Route 3: should you build your own AI agent?

Only if you have the technical capacity to run it. In return you get the most control.

Self-build platforms give you the AI engine and leave the rest to you. ElevenLabs is the clearest example: its agent plans run from $6 to $990 a month excluding taxes, with included call minutes and between 6 and 40 simultaneous calls on the paid tiers. The language model is billed separately on top, and ElevenLabs adds no telephony: you connect your own carrier, such as a SIP trunk, which bills you directly.

That makes three bills for one call, priced in two currencies. It suits a business with developers who want to choose the model, write the logic and connect it to their own systems. Your phone system connects by sending calls to the agent’s SIP address or forwarding to its number. See our ElevenLabs review and our guide to SIP trunking in South Africa.

Route 4: will AI come built into the mobile network?

Probably, but not yet in South Africa.

Operators in Europe, the US and Asia have started putting AI assistants into the network itself, so they work on an ordinary call without an app or a new number. As of 1 October 2026, we have found no South African operator that has publicly launched network AI calling. For a team that lives on cellphones, it is worth watching rather than waiting for. We cover the trend in Mobile AI: why the next AI assistant lives in your SIM.

How do the four routes compare?

Side by side, on what each needs and what each costs to run.

Route	Works with	Who sets it up	Cost shape	Main catch
1. Built-in add-on	3CX or Yeastar only	You or your reseller	Licence or add-on, plus AI usage	Tied to your platform and version
2. Call forwarding	Almost any number or system	Self-setup or done for you	Monthly plan, often plus per-minute	Forwarded calls may carry call charges
3. Self-build over SIP	Any system that can reach a SIP address	Your developers	Platform, model and carrier: three bills	You build and maintain the agent
4. Network AI	Mobile numbers	Your operator	Not yet priced in South Africa	Not available locally yet

Every AI voice provider in our record, eight of eight, can hand a call to a person. That is table stakes. What differs is what arrives with the call when it is handed over, and how many calls the AI can take at once: published plans range from one call at a time to ten or more.

A small-business owner in her tailoring workshop checking a smartphone — For most small businesses, the first job for AI is the call nobody was free to answer.

How do you add AI to your phone system, step by step?

Five steps, whichever route you take.

Pick the calls firstMissed calls, after-hours calls or the same three questions asked all day. Narrow jobs work best.

Check what your system allowsOn 3CX or Yeastar, ask about the AI add-on. On anything else, ask your provider how to forward calls and how forwarded calls are billed.

Trial it on part of your callsStart with no-answer or after-hours forwarding, or a second number, before the AI answers everything.

Set the handover properlyDecide who the AI transfers to, at what point, and what it tells them about the caller.

Measure resolution, not minutesTrack how many calls the AI handled without a person. Our AI voice agent health check and guide to telling if it is working show what to watch.

✓

Expect a partial win at first. In our analysis of 2,544 real calls to a live AI receptionist, fewer than 40% were handled end to end by the AI. Routing only the right calls to it, and a clean handover for the rest, matters more than which product you choose.

Our verdict

Adding AI to a phone system is a smaller job than most businesses expect. If you run 3CX or Yeastar, the vendor’s add-on is the most direct route. For everyone else, forwarding missed and after-hours calls to an AI receptionist keeps your number and your system and can be live quickly. Self-build is for teams with developers, and network AI is not here yet.

Our recommendation: start with the calls you miss today, forward only those, measure how many the AI resolves, then decide whether to give it more.

Find an AI voice agent that fits your setup

Tell us what phone system you run and which calls you want answered, and we will match you with providers who can work with it.

Hear one and get a pilot quote Compare AI voice agents

Frequently asked questions

Can I add AI to my existing phone system?

Usually, yes. If you run 3CX or Yeastar, both sell an AI receptionist add-on that works inside the phone system. On any other system or number, you can forward calls to an AI receptionist service. Neither route requires replacing your phone system or changing your number.

Do I need a new phone number for an AI receptionist?

No. Forwarding-based services answer calls forwarded from your existing number, and built-in add-ons answer on your existing lines. Some services do not port numbers at all and work only by forwarding, so you keep your number with your current provider.

Does an AI receptionist work with a Telkom landline?

Forwarding-based services can. AiSky, for example, says it works with existing Telkom, Vodacom, MTN, Cell C and Rain numbers by forwarding or SIP. Ask your provider how to set conditional forwarding on your line and how forwarded calls are billed.

How much does it cost to add AI to a phone system?

It depends on the route. Self-setup AI receptionist plans charge no setup fee; done-for-you setups we track cost from R3,950 to R6,950 or more, once-off. Monthly plans start at R849 before usage, and built-in add-ons add a licence or subscription plus AI usage. Our cost guide and calculator compare plans at your own call volume.

Can the AI transfer calls to my staff?

Yes. All eight AI voice providers in our record support handing a call to a person. Check what the AI passes on when it transfers, such as the caller’s name and reason for calling, and who it transfers to when nobody is free.

How long does it take to set up?

Self-setup services can be running quickly once forwarding is switched on; AiSky estimates about an hour. Done-for-you setups that write scripts and connect your systems typically take one to two weeks. Built-in add-ons depend on your reseller enabling them.

Should I let the AI answer every call?

Not at first. Start with missed and after-hours calls, measure how many the AI resolves without a person, and widen its job only when the numbers support it. In our study of a live AI receptionist, fewer than 40% of calls were handled end to end.

Keep reading

What is MCP, and does your phone system need one? AI voice agents: the full guide Compare AI voice agents What an AI voice agent really costs Replacing your system? How to choose a future-ready phone system Mobile AI: why the next AI assistant lives in your SIM

Sources: Product details, prices and limits are read from each provider’s own published pages and held as dated facts in the WhichVoIP record: 3CX AI Receptionist (sampled 30 September 2026) and 3CX pricing (3 August 2026); Yeastar AI Receptionist documentation (27 and 30 September 2026); AiSky (18 August 2026); SME Advantage (30 September 2026); BizAI pricing (27 September 2026); ElevenLabs agent pricing (30 September 2026); Aiployee and Le Roux Digital setup fees (27 and 30 September 2026). Call-handling figures are from WhichVoIP’s own analysis of 2,544 calls to a live AI receptionist. Network AI status as researched for our Mobile AI article, 1 October 2026. Verified 2 October 2026.