---
title: "Phone number validation - Amplia Reg"
description: "How to check a holder's phone number with the Amplia Reg validation API before creating an order, so text messages reach the holder."
canonical: "https://docs.lacunasoftware.com/en-us/articles/amplia-reg/integration/validate-phone"
locale: "en"
product: "Amplia Reg"
last_updated: "2026-10-08"
---

# Phone number validation - Amplia Reg

Amplia Reg sends the holder text messages, such as issue key 2 when the order is approved, so the order's phone number must be valid.
Order creation rejects an invalid phone number. To catch the problem earlier, for example while the customer is still filling in your
form, check the number with the validation API before creating the order.

> **Tip**
>
> Make sure you have completed the [Getting started](https://docs.lacunasoftware.com/en-us/articles/amplia-reg/integration/get-started) steps

Any API key can call this API: it requires no specific role.

## Validating a number

In .NET:

```cs
bool isValid = await ampliaRegService.ValidatePhoneNumberAsync("+5511999990000");
if (!isValid) {
	// Ask the customer to correct the phone number
}
```

Via API:

```plaintext
GET /api/users/phone-number/validation?phoneNumber=%2B5511999990000
```

The response body is `true` if the number is valid and `false` otherwise.

> **Note**
>
> Encode the number in the query string: the `+` of the international prefix must be sent as `%2B`, or it is read as a space. The .NET
> client encodes it for you.

## What is checked

The API applies the same check that order creation applies to the `phone` and `alternativePhone` fields of `contact`. A number that the
API accepts is also accepted when the order is created.

* **Country code**: the number must include the country code, as in `+5511999990000`. The leading `+` is optional, but the country code
  is not: without it, the first digits of the number are read as the country code, so `11999990000` would be read as a number from
  country code 1 (United States and Canada) and rejected.
* **Numbering plan**: the number must be valid for its country, with the right length and a valid area code and prefix.
* **Paraguay**: Paraguayan mobile numbers (`+595 9XX XXX XXX`) are also accepted when the numbering plan does not recognize them yet.
* **Formatting**: spaces, parentheses and hyphens are allowed, as in `+55 (11) 99999-0000`.

The check does not confirm that the line exists, or that it belongs to the holder.

> **Warning**
>
> An empty or missing `phoneNumber` returns `true`, because the API only rejects numbers it can tell are wrong. Check for empty values
> yourself.

## Tips

* **Ask for a mobile number** in the `phone` field. A valid landline passes the check, but the one-time codes that Amplia Reg sends by
  SMS, for example to let the holder join a videoconference or start a video identification, can only go to a mobile number.
* **Send the number in E.164 format** (`+5511999990000`, digits only after the `+`). Regular orders store the phone number in this format
  whatever the input, but [preapproved orders](https://docs.lacunasoftware.com/en-us/articles/amplia-reg/integration/preapproved-orders) store it as sent.

## See also

* [Getting started with integration](https://docs.lacunasoftware.com/en-us/articles/amplia-reg/integration/get-started)
* [Create an order](https://docs.lacunasoftware.com/en-us/articles/amplia-reg/integration/create-order)
* [Creating preapproved orders](https://docs.lacunasoftware.com/en-us/articles/amplia-reg/integration/preapproved-orders)
* [Error codes](https://docs.lacunasoftware.com/en-us/articles/amplia-reg/integration/error-codes)