Create Outbound Trunk

Creates an outbound trunk.

In version 2026-04-16, customers can create outbound trunks through the API even if the Outbound feature is not enabled on the account.

Request

HTTP Method: POST

URI Path: /v3/voice_out_trunks

Body Parameters

Name	Type	Nullable	Is Required?	Description
type	string	No	Yes	Must be voice_out_trunks.
attributes	object	No	Yes	Outbound trunk attributes object.

Data Attributes

Name	Type	Nullable	Is Required?	Description
name	string	No	Yes	The outbound trunk name.
external_reference_id	string	Yes	No	Optional identifier for the outbound trunk in the customer’s external system. Maximum length is 100 characters.
allowed_rtp_ips	Array of strings	Yes	No	Allowed RTP IP addresses for media traffic. Required when authentication_method.type is credentials_and_ip.
authentication_method	object	No	Yes	Authentication method object. Supported POST types: credentials_and_ip - use SIP credentials together with allowed IP addresses. twilio - use a Twilio Account SID for authentication. ip_only is not supported in POST requests.
on_cli_mismatch_action	string	No	Yes	Possible values: send_original_cli - pass the original From header value from your system to the destination without modification. reject_call - reject the call if the From header value does not match any DID allowed on the trunk. replace_cli - replace the CLI with one of the DIDs allowed on the trunk.
capacity_limit	integer	Yes	No	The capacity limit of the outbound trunk. Allowed values from 0 to 32767.
allow_any_did_as_cli	boolean	No	No	When set to true, all eligible DIDs can be used as CLI and the dids relationship must not contain explicit DIDs.
status	string	No	No	Possible values: active - the trunk can be used for outbound traffic. blocked - outbound traffic on the trunk is blocked. If set to null, the default value is active.
threshold_amount	string	Yes	No	The outbound trunk 24-hour threshold limit. Can be from 50 to 100000.
default_dst_action	string	No	No	Possible values: allow_all - allow calls to all destinations except the prefixes listed in dst_prefixes. reject_all - s to all destinations except the prefixes listed in dst_prefixes.
dst_prefixes	Array of strings	Yes	No	The destination prefixes allowed or rejected based on default_dst_action.
emergency_enable_all	boolean	No	No	Allows all eligible DIDs to be used for emergency calling on the trunk. Default value is false.
media_encryption_mode	string	No	No	Media encryption mode. Possible values: disabled - media encryption is turned off. srtp_sdes - use SRTP encryption with SDES key exchange. srtp_dtls - use SRTP encryption with DTLS key exchange. zrtp - use SRTP encryption with ZRTP key exchange.
callback_url	string	Yes	No	Can be null or a valid HTTP(S) URL.
force_symmetric_rtp	boolean	No	No	Enables symmetric RTP / COMEDIA mode.
rtp_ping	boolean	No	No	Enables RTP ping after the call is connected.
rtp_timeout	integer	Yes	No	Disconnects the call if RTP packets do not arrive within the specified time. Supported values are from 30 to 600 seconds.

See Outbound Trunk callback details for information about callback_url and the JSON callback payload.

Request Body Object Relationships

Title	Type	Description
dids	DIDs	The DID numbers explicitly allowed as CLI when allow_any_did_as_cli is false. DIDs must support voice_out feature to be selected.
emergency_dids	DIDs	The DID numbers explicitly enabled for emergency calling when emergency_enable_all is false. DIDs must support voice_out and emergency features and have emergency_enabled = true to be selected.

Authentication Method

The outbound trunk authentication is configured through the authentication_method attribute.

Supported authentication method types:

• credentials_and_ip - uses SIP credentials together with allowed IP addresses.

• twilio - uses a Twilio Account SID for authentication.

• ip_only is returned by GET endpoints but is not supported in POST requests.

Authentication Method Attributes by Type

credentials_and_iptwilio

Name	Type	Nullable	Is Required?	Description
allowed_sip_ips	Array of strings	No	Yes	The allowed originating SIP IPs.
tech_prefix	string	Yes	No	An optional technical prefix added before the destination number. The maximum length is 8 characters and only digits and # are supported.

Examples

credentials_and_iptwilioSelected emergency DIDs

http

POST /v3/voice_out_trunks HTTP/1.1
Host: api.didww.com
Content-Type: application/vnd.api+json
Accept: application/vnd.api+json
Api-Key: [API token]

{
  "data": {
    "type": "voice_out_trunks",
    "attributes": {
      "name": "Outbound trunk Name",
      "callback_url": null,
      "allowed_rtp_ips": [
        "0.0.0.0/0"
      ],
      "authentication_method": {
        "type": "credentials_and_ip",
        "attributes": {
          "allowed_sip_ips": [
            "0.0.0.0/0"
          ],
          "tech_prefix": null
        }
      },
      "on_cli_mismatch_action": "send_original_cli",
      "capacity_limit": 100,
      "allow_any_did_as_cli": true,
      "status": "active",
      "threshold_amount": "10000.0",
      "default_dst_action": "allow_all",
      "dst_prefixes": [],
      "emergency_enable_all": false,
      "media_encryption_mode": "disabled",
      "force_symmetric_rtp": false,
      "rtp_ping": false,
      "rtp_timeout": 30
    }
  }
}

curl

curl -i -X POST https://api.didww.com/v3/voice_out_trunks -H "Accept: application/vnd.api+json" -H "Api-Key: [API token]" -H "Content-Type: application/vnd.api+json" --data-raw '{"data": {"attributes": {"allow_any_did_as_cli": true, "allowed_rtp_ips": ["0.0.0.0/0"], "authentication_method": {"attributes": {"allowed_sip_ips": ["0.0.0.0/0"], "tech_prefix": null}, "type": "credentials_and_ip"}, "callback_url": null, "capacity_limit": 100, "default_dst_action": "allow_all", "dst_prefixes": [], "emergency_enable_all": false, "force_symmetric_rtp": false, "media_encryption_mode": "disabled", "name": "Outbound trunk Name", "on_cli_mismatch_action": "send_original_cli", "rtp_ping": false, "rtp_timeout": 30, "status": "active", "threshold_amount": "10000.0"}, "type": "voice_out_trunks"}}'

response

HTTP/1.1 201 Created
Content-Type: application/vnd.api+json

{
  "data": {
    "id": "03813615-da15-4e3b-8e0a-3ea64b2585de",
    "type": "voice_out_trunks",
    "attributes": {
      "name": "Outbound trunk Name",
      "callback_url": null,
      "allowed_rtp_ips": [
        "0.0.0.0/0"
      ],
      "authentication_method": {
        "type": "credentials_and_ip",
        "attributes": {
          "allowed_sip_ips": [
            "0.0.0.0/0"
          ],
          "tech_prefix": null,
          "username": "554******",
          "password": "fqe******"
        }
      },
      "on_cli_mismatch_action": "send_original_cli",
      "capacity_limit": 100,
      "allow_any_did_as_cli": true,
      "status": "active",
      "threshold_reached": false,
      "threshold_amount": "10000.0",
      "default_dst_action": "allow_all",
      "dst_prefixes": [],
      "emergency_enable_all": false,
      "media_encryption_mode": "disabled",
      "force_symmetric_rtp": false,
      "rtp_ping": false,
      "rtp_timeout": 30,
      "created_at": "2025-04-02T10:00:00.000Z",
      "external_reference_id": null
    },
    "relationships": {
      "dids": {
        "links": {
          "self": "https://api.didww.com/v3/voice_out_trunks/03813615-da15-4e3b-8e0a-3ea64b2585de/relationships/dids",
          "related": "https://api.didww.com/v3/voice_out_trunks/03813615-da15-4e3b-8e0a-3ea64b2585de/dids"
        }
      },
      "emergency_dids": {
        "links": {
          "self": "https://api.didww.com/v3/voice_out_trunks/03813615-da15-4e3b-8e0a-3ea64b2585de/relationships/emergency_dids",
          "related": "https://api.didww.com/v3/voice_out_trunks/03813615-da15-4e3b-8e0a-3ea64b2585de/emergency_dids"
        }
      }
    }
  },
  "meta": {
    "api_version": "2026-04-16"
  }
}

Other Responses

Code	Success	Description
422	No	Validation Error Object
400	No	Bad Request
401	No	Unauthorized