# HTTP OUT trunk settings reference

This reference describes the fields available when creating or editing an
HTTP OUT trunk, and the connection details shown in the trunk's credentials
window. The settings are grouped by the sections of the trunk form in the
DIDWW User Panel.

For configuration steps, see [Create an HTTP OUT trunk](how-to-guides/create-http-out-trunk.html) or [Manage HTTP OUT
trunks](how-to-guides/manage-http-out-trunk.html). This page covers trunk settings only.
For API request formats, attributes, and responses, see [Outbound SMS API
reference](../../outbound-sms-api/outbound-sms-api-reference.html).

## General settings

The **General** section identifies the trunk, sets the URL that receives
status callbacks, and restricts the IP addresses that can submit API requests.

| Field | Availability | Description |
| --- | --- | --- |
| Friendly name | Required | Unique name used to identify the trunk. The form suggests a name, for example `Outbound SMS trunk 1`, which you can replace. |
| Callback URL | Optional | URL on your server to which DIDWW sends status callbacks for messages submitted through this trunk. The value must be a valid URL. For example, `https://example.com/sms/callback`. DIDWW sends a status callback after it processes each message. When DLR events are enabled, DIDWW also sends the final delivery status from the carrier to this URL. Your application does not submit messages to this URL. It submits them to the Outbound SMS API, and the API response confirms only the submission. See [Status callbacks and delivery receipts](../../outbound-sms-api/status-callbacks-and-delivery-receipts.html). |
| Allowed IP addresses | Optional | IP addresses from which access to the API is allowed, in the format `(IPv4|IPv6)[/mask]`. For example, `203.0.113.10/32`. Entries in any other format are marked as invalid. When the field contains IP addresses, the API rejects requests from any other source. If the field is empty, all IP addresses are allowed. See [Authentication](../../outbound-sms-api/outbound-sms-api-reference.html#sms-out-spec-authentication). |

## Source address settings

The **Source Address Settings** section controls which DID numbers can be used
as the sender ID for outbound SMS.

| Field | Availability | Description |
| --- | --- | --- |
| Allow any DID(s) for SMS OUT | Optional | Controls how sender IDs are assigned. When the toggle is on, all DIDs with Outbound P2P SMS enabled in your account can be used as the sender ID. When the toggle is off, only the numbers in **Allowed source addresses** can be used. Default: on. |
| Available source addresses | Optional | DIDs that you can add to **Allowed source addresses** when **Allow any DID(s) for SMS OUT** is off. The list shows only DIDs that support outbound P2P SMS, with their **Country**, **Number**, and **Description**. Filters: **Source address**, **Description**, **Country**, and **Region**. |
| Allowed source addresses | Optional | DIDs that can be used as the sender ID when **Allow any DID(s) for SMS OUT** is off. Only the numbers in this list are available as sender IDs. |

If a message uses a source address that the trunk does not allow, DIDWW does
not send it. The status callback reports `code_id` `8` (SMS source address
is not allowed). See [Message processing status and
codes](../../outbound-sms-api/outbound-sms-errors-and-status-codes.html#callback-error-codes-http).

## Credentials and endpoint information

DIDWW generates the trunk credentials when the trunk is created. The
credentials window shows them together with the API endpoints and a summary of
the trunk's access settings. To open it, see [View HTTP OUT trunk
credentials](how-to-guides/view-http-out-trunk-credentials.html).

| Field | Description |
| --- | --- |
| Username | Username for HTTP Basic Authentication of Outbound SMS API requests. |
| Password | Password for HTTP Basic Authentication. The password is hidden until you click the eye icon. Regenerating the credentials replaces both the username and the password immediately. See [Regenerate HTTP OUT trunk credentials](how-to-guides/regenerate-http-out-trunk-credentials.html). |
| Host(s) | API endpoints for sending messages, one for each DIDWW location (**US, NY** and **NL, AMS**). HTTP OUT trunks have no location setting. To use a location, send your requests to its endpoint. For the endpoint URLs, including the global and other regional endpoints, see [Endpoints](../../outbound-sms-api/outbound-sms-api-reference.html#sms-out-spec-endpoints-headers). |
| Allowed IPs | IP addresses configured in **Allowed IP addresses**. Empty when all IP addresses are allowed. |
| Allowed Source Addresses | Source addresses that the trunk allows, as configured in **Source Address Settings**. Shows **Any** when **Allow any DID(s) for SMS OUT** is on. |

## Related resources

- [Create an HTTP OUT trunk](how-to-guides/create-http-out-trunk.html) -
  Create a trunk and configure the settings described on this page.
- [Manage HTTP OUT trunks](how-to-guides/manage-http-out-trunk.html) - Edit or
  delete an existing trunk.
- [HTTP OUT trunk](http-out-trunk.html) - Understand how message submission,
  credentials, and status callbacks work.
- [Outbound SMS API](../../outbound-sms-api/index.html) - Submit messages with
  the trunk credentials.
- [Sender ID Verifications](../../sender-id-verifications/index.html) - Verify
  Sender IDs for A2P messaging through an outbound trunk.