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

# Troubleshooting

> Common Vodafone Bulk Text integration issues and how to fix them.

Use this page to diagnose common authentication, campaign, Sender ID, and callback issues.

## Authentication issues

| Symptom                                   | Likely cause                              | Fix                                                                                            |
| ----------------------------------------- | ----------------------------------------- | ---------------------------------------------------------------------------------------------- |
| `401 Unauthorized` from the API           | Missing, expired, or invalid access token | Request a new token and retry the API call.                                                    |
| `invalid_grant` from the token endpoint   | Incorrect username or password            | Check the credentials supplied for the Bulk Text account.                                      |
| Token expires during processing           | Access tokens are short-lived             | Re-authenticate before requests or retry once after `401`.                                     |
| Request is rejected by the token endpoint | Wrong content type or form body           | Send `application/x-www-form-urlencoded` with `grant_type=password` and `client_id=ismstoken`. |

See [Authentication](/guides/authentication) for complete examples.

## Campaign request issues

| Symptom                                       | Likely cause                                | Fix                                                                                |
| --------------------------------------------- | ------------------------------------------- | ---------------------------------------------------------------------------------- |
| `415 Unsupported Media Type`                  | Request is not JSON                         | Send campaign requests with `Content-Type: application/json`.                      |
| Message is not accepted                       | Missing required field                      | Include `text`, `from`, and at least one `recipientInfo` entry.                    |
| Some recipients are skipped                   | Invalid recipient numbers                   | Review the `errors` array and correct the affected `msisdn` values.                |
| Account has no credits                        | Message processing returns a credit error   | Add credit or contact [bulktext.ie@vodafone.com](mailto:bulktext.ie@vodafone.com). |
| Scheduled message does not send when expected | `sendAt` is not UTC or has the wrong format | Use UTC in `yyyy-MM-ddTHH:mmZ` format.                                             |

## Sender ID issues

| Symptom                                  | Likely cause                                              | Fix                                                                  |
| ---------------------------------------- | --------------------------------------------------------- | -------------------------------------------------------------------- |
| Sender is not valid                      | `from` is not approved on the account                     | Call `GET /api/v2/senderlist` and use one of the returned values.    |
| Irish recipients do not receive messages | International non-ComReg Sender ID used for Irish traffic | Use a Type `0` ComReg Sender ID or Type `2` numeric Sender ID.       |
| New Sender ID is unavailable             | Registration is not complete                              | Contact [bulktext.ie@vodafone.com](mailto:bulktext.ie@vodafone.com). |

## Callback issues

| Symptom                           | Likely cause                                                  | Fix                                                                                         |
| --------------------------------- | ------------------------------------------------------------- | ------------------------------------------------------------------------------------------- |
| No webhook arrives                | Callback URL is not configured                                | Send your HTTPS endpoint to [bulktext.ie@vodafone.com](mailto:bulktext.ie@vodafone.com).    |
| Vodafone cannot deliver callbacks | Endpoint does not accept POST or TLS requirements are not met | Ensure your endpoint accepts `POST`, supports TLS 1.2 where required, and returns `200 OK`. |
| Duplicate callback processing     | Handler is not idempotent                                     | Store callback IDs or use `notifyId` plus timestamp/status to deduplicate.                  |
| DLR arrives late                  | Mobile network delivery status is delayed                     | Accept late DLRs and keep messages in an unconfirmed state until your timeout expires.      |
| Verification hash does not match  | Wrong verification key or hash input                          | Check the documented formula and confirm the verification key for your account.             |

## Legacy API issues

The v1 URL-encoded API returns plain-text status codes and messages, sometimes inside a `200 OK` HTTP response. Always inspect the response body before treating the request as successful.

See [Legacy API overview](/legacy/introduction) and the URL-encoded legacy endpoint in the Legacy APIs sidebar.