> ## Documentation Index
> Fetch the complete documentation index at: https://onextel-09023014.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# Validate a payload

> Check a send request for SMS, WhatsApp or RCS against the API before you send it.

Paste a request body below to see what the API would reject, before you spend a send on it. The
check runs in your browser: nothing is sent, and your payload and API key never leave the page.

API

Format
Samples:

<ol />

## What it checks

| API | Checks |
| - | - |
| [SMS, India](https://onextel-09023014.mintlify.site/api-reference/sms/send-sms-omni.md) | Required fields, `type` (`SI`, `OTP` or `SE`, case-sensitive), recipient format, DLT IDs, Unicode, custom references, URL shortening |
| [SMS, international](https://onextel-09023014.mintlify.site/api-reference/sms-international/send-sms.md) | `key`, the 2,500-message limit, numbers with country codes, Unicode |
| [WhatsApp template](https://onextel-09023014.mintlify.site/api-reference/whatsapp/send-template-message.md) | Envelope fields, business number, template name and language, components, buttons, carousels |
| [WhatsApp session message](https://onextel-09023014.mintlify.site/api-reference/whatsapp/send-session-messages.md) | Message type and its required fields, interactive buttons, lists and carousels |
| [RCS](https://onextel-09023014.mintlify.site/api-reference/rcs/send-template-message.md) | `messageType`, recipients, `ttl` format, `customParams` as a JSON string, rich card and carousel limits |
| [Fallback](https://onextel-09023014.mintlify.site/api-reference/omnichannel/fallback.md) | `fallback_id`, the `fallback` flag and `wait_time`, how `wait_time` interacts with an RCS `ttl`, and the SMS, WhatsApp or RCS fallback message, on any primary channel |

Every finding names the field, says what is wrong, and where the API rejects it, gives the response
you would get back — for example `invalid type` with status 700.

It also catches two mistakes that look valid:

* **Long IDs sent as numbers.** A 19-digit DLT template ID written without quotes is rounded by any
  JavaScript that parses the JSON on its way to OneXtel, such as a browser, a Node service or a
  no-code tool. Quote every ID.
* **Numbers that cannot receive.** `/send_sms` accepts and bills a recipient that is not a real
  mobile number. The validator flags anything outside the 6–9 mobile series.

## What it cannot check

Some rejections depend on your account, so only a real send reveals them:

* whether the template is approved, and approved for this sender
* whether the message body matches the registered DLT template word for word
* whether the sender ID, entity ID and template belong to your API key
* your balance and sending limits

For what each delivery failure means, see the error codes for
[India SMS](https://onextel-09023014.mintlify.site/api-reference/sms/error-codes.md),
[WhatsApp](https://onextel-09023014.mintlify.site/api-reference/whatsapp/error-codes.md) and [RCS](https://onextel-09023014.mintlify.site/api-reference/rcs/error-codes.md).

## Reading the results

| Level | Means |
| - | - |
| **Error** | The API rejects this, or the message cannot be delivered as written |
| **Warning** | The API accepts it, but the message may not arrive as intended, or may cost credit for nothing |
| **Note** | Correct, with a consequence worth knowing before you send |


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