If you're building a customer-facing service in New Zealand you've probably wanted a single phone number that handles both SMS and voice calls. It's a reasonable thing to want. Unfortunately, it's not possible in New Zealand.
This guide explains why, and what to do instead.
The Short Answer
🇳🉑 In New Zealand, A2P Messages cannot be sent from a mobile number. Short Codes do not support Voice.
Business SMS (A2P) in NZ runs on Short Codes (3 to 6-digit numbers). Voice calls run on standard landline or mobile numbers. The two number ranges are operated separately by the carriers and aren't interoperable. This is a carrier-level constraint set by Spark, One NZ and 2degrees, not a TNZ choice. No NZ provider can change it.
Why It's Not Possible
New Zealand's mobile networks split business-to-consumer messaging and voice into two separate worlds.
SMS lives on Short Codes
Application-to-person (A2P) SMS in New Zealand must be sent from a Short Code: a 3 to 6-digit number authorised by the carriers and monitored by the Department of Internal Affairs. Short codes aren't dialable for voice. You can't pick up the phone and call 4567. The number format simply doesn't exist on the voice network.
You also can't send business SMS from a normal 021/022/027 mobile number. The carriers block it to keep the channel free of the spam that other countries deal with. See Understanding SMS Short Codes for the full rules.
Voice lives on landline / mobile numbers
Voice runs on standard NZ phone numbers: landlines (e.g. +64 9 nnnnnnn) or mobile numbers. These can be ported to a SIP provider and answered by a softphone, a PBX, or an AI agent. But they don't receive SMS for business use.
The two ranges don't overlap
The short code range and the landline/mobile range are administered separately by the carriers and the regulator. There's no bridging between Voice and Short-Code SMS.
⚠️ This is a network-level constraint, not a TNZ limitation.
Any NZ SMS provider you ask (TNZ, the carriers themselves, anyone else) will give you the same answer. If a provider claims otherwise, ask them which exact number they'd provision and confirm with the carriers before committing.
The Recommended Setup
The right pattern is two numbers: a Short Code for SMS, a SIP landline for voice, with consistent branding on both so the customer doesn't notice the split.
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SMS: NZ Short Code
Built-in shared Short Code on signup (free, instant) or a dedicated 4 or 6-digit code for brand recognition. Supports two-way SMS and bulk send. See Understanding SMS Short Codes.
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Voice: Landline (or mobile)
A standard NZ landline or mobile number. New numbers can be provisioned, or you can port an existing number to TNZ.
Making the two numbers feel like one
- Mention both in confirmation messages. An SMS reminder can include "reply STOP to opt out, or call us on 09 nnn nnnn for help" so the customer knows which channel to use for what.
- Use the SMS for short transactions, voice for longer ones. Two-way SMS handles appointment confirmations and quick questions; voice handles support and account changes.
Why Australia is Different
In Australia, a Virtual Mobile Number (VMN) can handle both SMS and voice on the same number. AU carriers permit application-to-person SMS to run over standard mobile-format long codes, so a single number works for both.
If you're a NZ business sending to Australian recipients, an AU VMN is a good fit.
A few things you might read online that aren't accurate for New Zealand:
- "Provider X gives you a single NZ number for SMS and voice." Worth confirming with that provider exactly which number range they'd allocate. Chances are, they have a SIM in a phone that's prone to error or carrier blocks.
- "You can send business SMS from your 021/022/027 mobile." You can technically send, but the NZ networks and the Department of Internal Affairs actively block this kind of traffic. It won't deliver reliably and may flag your number.
- "Short codes can receive voice calls." They can't. Short codes exist only on the SMS routing layer.
FAQ
I'm building an AI agent that needs both SMS and voice. What do I do?
Provision both: a Short Code for SMS (TNZ assigns a built-in code on signup) and a telephone number for voice. Connect them to your agent through the TNZ API for SMS and a SIP integration for voice. Many AI agent platforms accept both channels and can present them as a single conversation thread.
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Can I port my existing landline to TNZ and have it accept SMS?
You can port the number for voice; that part works. But the same number won't accept A2P SMS for business use, because the NZ networks don't support SMS on landline-format numbers. The voice side will work fine; SMS continues to need a Short Code.
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Will this ever change?
Unlikely in the short term. The current NZ rules exist to keep the channel clean: NZ has far less SMS spam than markets. Any change would need to come from the carriers and the regulator.
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What about WhatsApp, RCS, or other channels?
Different channels follow different rules. WhatsApp identifies you by display name and business profile, not by phone number in the same way, so it can coexist with both an SMS Short Code and a voice number. See Onboarding WhatsApp Business Account if you'd like to add WhatsApp alongside SMS and voice.
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Where can I get help designing the right setup?
Talk to the TNZ team. We'll recommend a configuration based on your use case and let you know what's possible end-to-end.
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