How to Forward Your Telstra, Optus or TPG Business Number to an AI Receptionist

Here is the thing most business owners get wrong about AI phone answering: they assume they have to change their number.

You don't. Your number stays exactly where it is, on your van, your Google Business Profile, your invoices, ten years of printed flyers. What changes is what happens in the seconds after someone dials it. A single call diversion rule on your Telstra, Optus or TPG service is the entire integration. No new hardware, no port, no NBN technician, no phone system rebuild.

But the rule you choose matters enormously, and the one detail that trips up almost everyone is that your voicemail is competing with your AI receptionist for the same call, and by default, voicemail usually wins.

This guide covers the three routing patterns Australian businesses actually use, the exact codes and portal steps for each major carrier, why 20 seconds is the number that matters, and how to test the whole thing in four minutes.

First, understand what a diverted call actually is

When you divert a number, the network splits the call into two legs.

Leg one is the caller dialling your business number. Leg two is your carrier placing a fresh outbound call from your number to the destination, in this case, your AIVOX AI voice agent number.

Three practical consequences follow from that, and they explain most of the problems people run into:

1. You pay for leg two. Your carrier bills the forwarded leg as if your service made that call. On a plan with unlimited standard national calls this is usually included, but confirm it with your carrier before you divert a high-volume line. Prepaid services are frequently excluded from conditional diversion altogether.
2. The caller's number is still visible. Australian networks pass the original caller's CLI through the diversion, which is what lets your AI receptionist greet a repeat caller, log the number against a CRM record, and send you an SMS with a callback number. Without CLI passthrough, an automated answering service would be flying blind.
3. The network decides, not your handset. Carrier-level diversion happens in the exchange before your phone is involved. That is why it keeps working when your mobile is flat, your nbn modem is unplugged, or the shop's power is out, the failure modes that cost you the most expensive leads.

The three routing patterns (pick one before you dial anything)

Almost every deployment we see is one of three shapes. Decide which one fits how you actually work, because they use different codes.

Pattern 1: AI answers first, then transfers to you if needed

Every call goes straight to the AI receptionist. It greets the caller, qualifies why they're ringing, handles the routine stuff end to end, hours, pricing, address, booking a job, and warm transfers to your mobile or office line only when the call genuinely needs a human.

This is unconditional diversion. Your phone doesn't ring at all unless the AI passes the call through.

Who this suits: Trades on a roof or under a sink. Clinics where reception is already stretched. Any business where more than half of inbound calls are questions a well-built AI voice agent can answer without you. Also the right choice for a dedicated 1300/1800 marketing line where you want every enquiry captured and scored.

The trade-off: You lose the ability to grab a call the instant it comes in. For businesses where the owner's relationship is the product, high-value legal or finance enquiries, for instance, that can matter. Configure a low transfer threshold, or use Pattern 2.

Pattern 2: You answer first, AI catches what you miss

Your phone rings normally. If nobody picks up within a set window, the network hands the call to your AI receptionist instead of dropping it into voicemail.

This is Call Forward No Answer, and it is the single highest-return configuration for most small businesses, because it changes nothing about your day and eliminates the missed call entirely. It is the reason a missed calls capture service beats voicemail so decisively: a voicemail recovers maybe one caller in five, while a conversation that books the job recovers most of them.

The window to set is 20 seconds. More on why below, it's the part people get wrong.

Pattern 3: The safety net: phone off, out of range, or already on a call

Two more conditions exist, and they cover the gaps Patterns 1 and 2 leave open:

• Call Forward Unreachable fires when your phone is switched off, in flight mode, flat, or out of coverage. Country jobs, basements, plant rooms, overseas trips.
• Call Forward Busy fires when you're already on a call. This is the quiet leak nobody measures, the second caller during a busy Monday morning, who rings a competitor thirty seconds later.

You can stack these. No answer, unreachable and busy are three independent rules, all pointing at the same AI receptionist number. Set all three and your line becomes genuinely unmissable, an after hours call answering service that also covers the middle of your working day.

Which pattern to choose

Telstra: mobile services

Telstra documents four diversion types and one code pattern for all of them. The type codes are 21 (all calls), 61 (no answer), 62 (unreachable) and 67 (busy).

Open your dial pad and enter the sequence exactly as shown, then press call. You will get an on-screen confirmation within a couple of seconds.

Turn a diversion on: ** [type code] * [AIVOX number] * 11 #

So to send unanswered calls to an AI receptionist on 0X XXXX XXXX, you'd dial **61*0XXXXXXXXX*11#.

The trailing 11 is the basic service code for voice, it tells the network to divert voice calls only. Telstra's small business support page shows both *10# and *11# in different places; 11 is the voice service code and is the safer choice. The shorter GSM form **61*[number]# also works on most services if the full sequence is rejected.

Set the ring time before it diverts (Pattern 2): ** 61 * [AIVOX number] ** 20 #

Telstra allows 15, 20, 25 or 30 seconds. Use 20.

Turn a diversion off: ## [type code] # , for example ##61# Check what's currently set: *# [type code] #, for example *#61# Nuclear option: ##002# erases every active diversion at once. Run this first if you've inherited a service and don't know what's configured.

Critical Telstra-specific step — deal with MessageBank first. See the next section. Telstra documents ##004# to remove the conditional diversions to MessageBank, and DCF Off sent by SMS to 144 to switch off Message2Txt.

Telstra's own reference: How do I forward calls on my mobile?

Telstra: fixed line and nbn home or business phone

Fixed voice is a different product with a different code family, and it is the number one reason a diversion "doesn't work" — someone tried a mobile code on a desk phone.

Lift the handset, wait for dial tone, then enter the code and hang up. Telstra's current home-phone guidance documents *21[number]# for immediate diversion, *61[number]# for no answer and *24[number]# for busy, cancelled with #21#, #61# and #24#.

Note there are no double asterisks on fixed services, and the ring-time setting is managed at the network level rather than by handset code — you'll need to ask Telstra to change it.

If you have a PBX or an on-premise phone system (Panasonic, NEC, Avaya, a 3CX install), your handset codes are the system's codes, not Telstra's. You have two options: divert at the carrier level so it happens before the PBX sees the call, or configure an overflow rule inside the PBX pointing at your AI number. The second is usually better, because a PBX can route by time of day and by extension.

Optus: mobile services

Optus mobiles run the same GSM code set as Telstra, so **21*[number]#, **61*[number]#, **62*[number]# and **67*[number]# all behave as expected, cancelled with ##21# and friends.

Optus's current device guidance, though, sends you through the handset menu instead, which is easier to get right. On Android the path is typically Phone app → Settings → Supplementary services → Call forwarding, then choose the divert type and enter the destination. On iPhone, Settings → Apps → Phone → Call Forwarding exposes unconditional diversion only; for conditional rules you need the dial codes above.

Ring time on Optus mobile follows the same pattern as Telstra: append the delay in five-second increments, e.g. **61*[AIVOX number]**20#. Also check whether voicemail is intercepting first — Optus voicemail behaviour varies by plan, so confirm the divert-to-voicemail setting is cleared for the condition you're using.

Optus: fixed line and Optus Loop

Optus fixed voice does not use the mobile codes. The long-standing Optus fixed-line pattern is *78[number] to activate and #78 to cancel, with two confirmation beeps — but this varies by product, so verify against your exact service before you rely on it.

If you're on Optus Loop (their hosted business voice platform), you're in a different world again: Loop has its own feature access codes for Call Forwarding Always, Busy, No Answer and Not Reachable, plus hunt groups and call queues. Loop's own Feature Access Codes reference lists them, and the admin portal is generally a better place to configure this than a handset code — it supports time-of-day schedules, which turns an out of hours call answering service into a set-and-forget rule.

TPG: business and nbn voice

TPG doesn't use star codes. Everything is done in the portal, which is genuinely simpler.

1. Sign in to My Account at tpg.com.au
2. Open View nbn Home Phone Service Account (you may see nbn Digital Voice Service Account instead, depending on your product)
3. Open the Service Control Panel
4. Under Call Forwarding/Diverting, enter your AIVOX number against the diversion type you want

TPG offers divert all calls, divert if busy and divert if no reply. All types are off by default.

Three TPG-specific gotchas worth knowing:

• "Divert if no reply" will not work if you have also set "divert all incoming calls." Unconditional beats conditional. Pick one.
• International destinations are not supported. Not an issue for an Australian AI receptionist, but worth knowing if you've ever tried to forward offshore.
• TPG Voice has no voicemail feature at all on some products — which means unanswered calls currently just ring out. That's the worst possible outcome and the easiest to fix.

Standard call rates apply to forwarded calls; TPG's talk add-ons cover forwarding to standard national numbers and mobiles. References: nbn Home Phone Features and the TPG Voice Features Guide.

13, 1300 and 1800 numbers

Inbound numbers aren't diverted with handset codes at all. They're routed in your inbound number provider's portal, where you point the answer point at your AI receptionist number. The upside is that inbound routing platforms usually support answer-point rules by time of day, day of week and even caller state — so you can send business hours to your team and everything else to a 24/7 call answering service without touching a handset.

The 20-second rule, and the voicemail race nobody warns you about

This is the part that determines whether your setup actually works.

Australian mobile services divert to voicemail at around 15 seconds by default. Telstra's documented default for Call Forward No Answer is 15 seconds, and that default points at MessageBank.

So picture what happens if you set a 20-second diversion to your AI receptionist without touching voicemail. The caller rings. At 15 seconds, voicemail answers. Your 20-second rule never fires, because the call was answered — by voicemail. You'll conclude the AI receptionist "doesn't work," when in fact it never got the call.

The fix, in order:

1. Clear the voicemail diversions first. On Telstra mobile, ##004# removes the conditional diversions to MessageBank, and DCF Off by SMS to 144 disables Message2Txt. Both need to be off for the line to have no voicemail service.
2. Then set your diversion to the AI number with an explicit 20-second delay.
3. Verify with *#61# that the destination is your AIVOX number and not 101.

Why 20 seconds rather than 15 or 30? Fifteen is roughly four rings — enough time to fish a phone out of a pocket, but not enough to put down a tool, pull off a glove and swipe. Thirty is past the point where Australian callers start hanging up; abandonment climbs sharply once a call passes about five rings. Twenty seconds gives you a real chance to answer and still hands the caller to your AI voice agent while they're engaged rather than irritated.

One more constraint: double diversion often fails. If your office line already forwards to your mobile, and your mobile then forwards to the AI, some networks will refuse the second hop. Point both services directly at your AI number instead of chaining them.

Test it in four minutes

Do this from a phone that is not the phone you're diverting, and do it before you tell any customer the number is live.

1. Check the rule registered. Dial *#21# or *#61# on the diverted service. Confirm the destination number shown is your AIVOX number, digit for digit, in full national format with no spaces.
2. Call from an unknown number. Ring your business number and let it run the full window. Time it with your watch — if the AI picks up noticeably earlier or later than you configured, something else is intercepting.
3. Confirm your caller ID arrived. Check that the call log in your AIVOX dashboard shows the actual number you called from, not your own business number or a blank.
4. Test the transfer path (Pattern 1). Ask the AI for something that should escalate and confirm the warm transfer actually reaches a human, and that the transferred leg has decent audio.
5. Test the failure path (Pattern 3). Turn the phone off completely, ring the number, and confirm the unreachable rule fires.
6. Ring during a live call (Pattern 3) to confirm the busy rule fires.

If step one shows the wrong destination, run ##002# and start again.

Quick troubleshooting

Forwarding is the plumbing. The conversation is the product.

Getting the diversion right takes about four minutes. Getting the call right is the actual work — and it's where the difference between a useful AI receptionist in Australia and an infuriating robot lives.

Three things decide it:

Latency. If your AI takes more than roughly a second to respond, callers talk over it, and the whole thing collapses into an awkward mess. This is an architecture problem, not a prompt problem — we've written about why most AI voice agents fail on design and latency and the zero-latency engineering behind voice agents that sound human.

The script. A diverted call arrives with no context, so the first ten words have to establish who answered and why the caller should keep talking. Our guide to writing the perfect script for an AI calling bot covers the openers and escalation rules that work on real inbound calls.

Knowing when to hand over. The transfer decision is what separates a genuine agentic AI phone representative from an answering machine with better manners. It should escalate on urgency, on value, and on frustration — and it needs a rule for what happens when the transfer isn't answered either.

What "right" looks like also varies sharply by trade. A healthcare clinic needs triage and privacy discipline; a plumber or electrician needs job address, fault description and an urgency read; a law firm needs conflict checks before anything else; a real estate agency needs the listing address and buyer intent captured while the caller is still hot.

FAQ

Will forwarding my number change my phone number? No. Diversion happens inside the carrier network after someone dials your existing number. Your number, your listings and your marketing all stay exactly as they are.

Does my phone still ring if I forward to an AI receptionist? That depends on the pattern you choose. Unconditional diversion (code 21) sends calls straight to the AI and your phone stays silent. No-answer diversion (code 61) rings your phone first and only hands over calls you don't pick up.

How long does it take to set up? Two to four minutes on a mobile using dial codes, or about five in a carrier portal for a fixed or nbn service. Testing properly takes another few minutes and is worth doing.

Does the AI receptionist know who is calling? Yes. Australian networks pass the original caller's number through the diversion, so your AI voice agent can log the number, recognise repeat callers and give you a callback number even if the caller never states it.

Can the AI transfer the call to me? Yes — that's Pattern 1. The AI answers first, handles what it can, and warm transfers to your mobile or office line when the call needs a person.

What does call forwarding cost? The diversion feature itself is usually free, but your carrier bills the forwarded leg as an outgoing call from your service. Plans with unlimited standard national calls generally cover it. Confirm with your carrier before diverting a high-volume line.

Can I forward only after hours? Yes, three ways: switch the rule on and off manually at close of business, use a carrier or hosted-voice product with time-of-day routing, or leave a no-answer rule on permanently so your AI covers both after-hours calls and daytime misses.

Does this work on prepaid? Often not. Many prepaid plans exclude conditional diversion. Check with your carrier, and be aware MVNOs don't necessarily inherit the parent network's diversion features.

Your number already works. The calls are already coming. The only question is what answers them at 6:40pm on a Thursday.

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