> ## Documentation Index
> Fetch the complete documentation index at: https://plivo.com/docs/llms.txt
> Use this file to discover all available pages before exploring further.

# Troubleshooting

> Resolve Lookup API errors with a reference of error codes and descriptions

You can use the Plivo Lookup API to avoid sending messages to invalid or inaccessible numbers, which can help you save money on your campaign.

The Lookup API determines whether a number is a real phone number and belongs to an operator. If a number is invalid or the lookup fails, our server returns an error code and a message that explains the problem.

For example, consider a lookup request for the phone number 1-202-555-1234:

```
https://lookup.plivo.com/v1/Number/12025551234?type=carrier
```

A successful Lookup API response returns an HTTP status code of 200.

An unsuccessful response returns an `api_id`, an error code, and an error message.

```json theme={null}
{
    "api_id": "",
    "error_code": 404,
    "message": "Phone number is invalid or does not exist."
}
```

This table shows the potential error codes and descriptions that an unsuccessful lookup request might return.

## Plivo Lookup Error Codes

| **HTTP Status Codes** | **Plivo Error Codes** | **Reason**                                                       | **Description**                                                                                                                                                                                                                                                                                                   |
| --------------------- | --------------------- | ---------------------------------------------------------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| 401                   | 401                   | Auth ID and/or Auth Token is invalid.                            | You receive this response when you use **invalid credentials** to access the API.                                                                                                                                                                                                                                 |
| 402                   | 402                   | Account does not have sufficient balance to fulfill the request. | **Prepaid account** has **insufficient balance**. This error is not applicable for postpaid customers. Please recharge your account.                                                                                                                                                                              |
| 403                   | 403                   | Account is forbidden from accessing resource.                    | Customer has **not been subscribed to the Lookup Service**. Please contact [Plivo support](https://support.plivo.com/hc/en-us/requests/new?ticket_form_id=360000156292).                                                                                                                                          |
| 404                   | 404                   | Phone number is invalid or does not exist.                       | Phone number is either **invalid** or **doesn’t exist**.                                                                                                                                                                                                                                                          |
| 400                   | 160                   | Request type not specified or is invalid.                        | Lookup API requires the query parameter **type** to be set in the request. This error occurs when this **parameter is missing** or if the value passed with the parameter is invalid.<br /><br />Check the [Number Lookup API documentation](/lookup/api/lookup-phone-number/) to learn about the API parameters. |
| 500                   | 300                   | Failed to process request due to internal server failure.        | Plivo is unable to process the API request due to internal issues.<br /><br />Contact [Plivo support](https://support.plivo.com/hc/en-us/requests/new?ticket_form_id=360000156292).                                                                                                                               |
| 5XX                   | NA                    |                                                                  | Contact [Plivo support](https://support.plivo.com/hc/en-us/requests/new?ticket_form_id=360000156292).                                                                                                                                                                                                             |