---
title: "OTP and transactional notifications on every channel your users have"
description: "Send one-time passwords by WhatsApp authentication templates, SMS, RCS or voice call, with fallback between channels and delivery status for every code."
canonical: "https://omnichannels.ai/solutions/otp-notifications/"
language: "en"
updated: "2026-10-10"
publisher: "BroadNet Technologies"
brand: "OmniChannels.ai"
---

# OTP and transactional notifications on every channel your users have

Canonical: https://omnichannels.ai/solutions/otp-notifications/
Language: en
Publisher: OmniChannels.ai by BroadNet Technologies

Deliver sign-in codes, payment confirmations and service alerts on WhatsApp with copy-code, one-tap or zero-tap templates, by SMS from a registered sender ID, by RCS, or by a voice call that reads the code aloud.

**Short answer:** OmniChannels.ai delivers one-time passwords and transactional alerts on WhatsApp, SMS, RCS and voice. WhatsApp authentication templates offer copy-code, one-tap or zero-tap delivery. SMS goes out from a registered sender ID over BroadNet's operator connectivity, and voice OTP reads the code aloud, including in Arabic. You set a fallback order between channels, and delivery statuses reach your system by webhook. Your application generates and checks the code.

## What OTP and notification delivery includes

- **WhatsApp authentication templates:** Send codes in Meta's authentication format, with fixed preset text, an optional expiry line and a security reminder.
- **Copy-code, one-tap and zero-tap:** Copy-code works on any phone. One-tap and zero-tap fill the code into your Android app and need integration work on your side.
- **SMS OTP from a registered sender ID:** Reach users without WhatsApp or mobile data, using a sender ID registered for transactional traffic, with HLR lookup to check numbers.
- **RCS from a verified sender:** Send codes from a verified, branded RCS sender on supported phones, with automatic SMS fallback where RCS is not available.
- **Voice OTP:** A call reads the code aloud with text-to-speech, including in Arabic, for users who cannot receive messages or need accessibility support.
- **Fallback between channels:** Set an order per flow, such as WhatsApp first, then SMS, then a voice call if delivery is not confirmed in time.
- **Delivery status for your system:** Submitted, sent, delivered, read, failed and rejected events reach your backend by webhook, in one format for every channel.
- **Delivery reports:** See status per message, filter by date and export to CSV to investigate slow or failed codes.

## Which OTP delivery method fits your users?

| Item | Details |
|---|---|
| WhatsApp copy-code | A button copies the code for pasting into your app or website. No app changes needed. |
| WhatsApp one-tap | A button opens your Android app and passes the code. Needs Android app integration. |
| WhatsApp zero-tap | The code is passed to your Android app in the background with no tap. Needs Android app integration and Meta's terms. |
| SMS OTP | Works on any mobile phone without data. Needs a registered transactional sender ID in many markets. |
| RCS OTP | Branded, verified sender on RCS-capable phones, with automatic SMS fallback elsewhere. |
| Voice OTP | Code read aloud by text-to-speech, including Arabic. Provisioned with your account team. |

## How to launch OTP delivery

1. **Map your verification flows:** List where codes are sent, such as sign-up, login, password reset and payments, and the countries your users are in.
2. **Set up the channels:** Create a WhatsApp authentication template, register a transactional SMS sender ID, and arrange RCS and voice OTP if you need them.
3. **Connect the API and webhooks:** Call the REST API from your backend, choose the fallback order and point delivery webhooks at your system. Test access sends to your own verified numbers.
4. **Add security and fraud controls:** Set short expiry, single use, attempt limits, rate limits and country allow-lists in your application.
5. **Test on real devices, then go live:** Check delivery and timing on each operator and channel, then monitor how many codes are sent compared with codes entered.

## Who should use OmniChannels.ai for OTP and alerts?

### A good fit when

- You verify sign-ups, logins or payments by phone number.
- Your users are in markets where WhatsApp is common but some still need SMS or a voice call.
- You want delivery status per code so support can see why a user did not receive one.
- You send codes and service alerts in Arabic and English.

### Good to know before you start

- OmniChannels.ai delivers codes; generating, storing and validating them is your application's job.
- Phone-based OTP is weaker than app-based authenticators or passkeys because of SIM-swap and interception risks.
- WhatsApp authentication templates cannot contain links, media or emoji, and their text is preset by Meta.
- Fallback can deliver more than one message for the same code; set wait times so users are not confused.
- Meta charges WhatsApp authentication messages by country, SMS is billed per segment and voice per call; confirm current rates.

## OTP and notification questions

### What is the difference between copy-code, one-tap and zero-tap?

Copy-code shows a button that copies the code for the user to paste. One-tap opens your Android app and passes the code. Zero-tap passes the code to your Android app with no tap. One-tap and zero-tap need Android app integration; copy-code does not.

### When should we use voice OTP?

Use a voice call as a last fallback when a message is not delivered, for landline numbers, or for users who prefer to hear the code. The call reads the code aloud with text-to-speech, including in Arabic.

### How long should a code be valid?

Keep it short and accept each code only once. NIST guidance limits out-of-band authentication to 10 minutes, and many businesses use shorter windows for logins and payments. WhatsApp authentication templates can show an expiry line so users know the deadline.

### What is SMS pumping and how do we prevent it?

SMS pumping, or artificially inflated traffic, is fraud where bots request codes to numbers that earn the attacker a share of the fees. Prevent it in layers: bot checks before sending, allowing only countries you serve, rate limits per number and IP, and alerts when codes sent rise without codes entered.

### Which channel should we send OTPs on first?

It depends on your users. WhatsApp offers a branded message with copy-code or autofill where users have data. RCS gives a verified sender on supported phones. SMS reaches almost any phone, and voice covers the rest. Many teams start on one and fall back to the next.

### Can we put a sign-in link in a WhatsApp OTP?

No. Meta's authentication templates cannot contain links, media or emoji. Send links in a separate utility template if your flow needs one.

Updated: 2026-10-10