# Create a gateway on a SIP trunk

`POST /v1/voice/trunks/{trunk_id}/gateways`

Adds a gateway address for forwarding inbound calls to this trunk.

Gateways are tried in `priority` order, lowest first, until one answers.
Gateways with equal priority share calls evenly. `sip_uri` identifies the
peer host, while `destination_format` and `origination_format` control the
called and calling number formats. Both number formats default to E.164.

A SIP URI already registered on this trunk returns `409 Conflict`. An
invalid SIP URI, a SIP URI carrying a user part, or a malformed number
format returns `422`. A trunk outside the workspace returns `404 Not Found`.
A trunk without inbound calling enabled returns `412 Precondition Failed`.

A trunk supports at most 20 gateways. Creating another returns 422; delete a gateway before adding its replacement. SIP ports must be between 1 and 65535.

## Code samples

**TypeScript**

```ts
const gateway = await bird.voice.trunks.gateways.create("TRUNK_ID", {
  sip_uri: "sip:pbx.example.com:5060",
  priority: 0,
  destination_format: "1234#{number}",
});
console.log(gateway.id, gateway.priority);
```

Examples: [TypeScript](/docs/api/reference/create-voice-trunk-gateway.ts.md) · [Python](/docs/api/reference/create-voice-trunk-gateway.py.md) · [Go](/docs/api/reference/create-voice-trunk-gateway.go.md) · [PHP](/docs/api/reference/create-voice-trunk-gateway.php.md) · [CLI](/docs/api/reference/create-voice-trunk-gateway.cli.md) · [MCP](/docs/api/reference/create-voice-trunk-gateway.mcp.md) · [cURL](/docs/api/reference/create-voice-trunk-gateway.curl.md)

## Example response `201`

```json
{
  "id": "vtg_01krdgeqcxet5s7t44vh8rt9mg",
  "trunk_id": "spt_01krdgeqcxet5s7t44vh8rt9mg",
  "sip_uri": "sip:pbx.example.com:5060",
  "priority": 0,
  "origination_format": "+{number}",
  "destination_format": "+{number}",
  "created_at": "2026-05-20T09:14:52Z",
  "updated_at": "2026-05-25T16:42:01Z"
}
```

## Path parameters

- `trunk_id` (string)

## Request body

- `sip_uri` (string, required): SIP URI an inbound call to this trunk should be forwarded to. Give the host only, with an optional port: which number is dialed there comes from `destination_format`, so a URI carrying a user part is rejected.
- `priority` (integer, required): The order gateways are tried in, lowest first. Give two gateways the same priority to share calls between them evenly.
- `origination_format` (string)

  How this gateway wants the calling number spelled. Write a template whose
  `{number}` stands for the number without its leading `+`; the result is
  stated in the `P-Asserted-Identity` header of the delivered call.

  Omit it for E.164, which is `+{number}`. The template may add digits,
  letters and the characters `-_.!~*'()&=+$,;?/%#` around `{number}`, which
  may appear at most once, and anything else in braces is rejected so a
  misspelled placeholder cannot reach a call.

  A format with no `{number}` at all states the same identity on every call,
  which is what a peer that only accepts one authorized number wants. The
  call then carries nothing about who really called.
- `destination_format` (string)

  How this gateway formats the dialed number. In the template, `{number}`
  represents the number without its leading `+`. The result is placed before
  the `sip_uri` host. For example, `1234#{number}` formats `+31201234567` as
  `sip:1234#31201234567@pbx.example.com:5060`.

  Omit it for E.164, which is `+{number}`. A format with no `{number}` at all
  sends every number this trunk answers to one fixed number, so
  `777000447973` reaches `sip:777000447973@pbx.example.com:5060` whatever was
  dialed. The same rules as `origination_format` apply to what the template
  may contain.

## Response body

- `id` (string, required): Unique identifier for this gateway.
- `trunk_id` (string, required)
- `sip_uri` (string, required): SIP URI an inbound call to this trunk is forwarded to. The host only: which number is dialed at that host comes from `destination_format`, because it changes with every call.
- `priority` (integer, required): The order gateways are tried in, lowest first. Gateways sharing a priority take an equal share of calls, and any of them may be tried first on a given call.
- `origination_format` (string, required)

  How the calling number is spelled to this gateway, as a template whose
  `{number}` stands for the number without its leading `+`. It is stated
  in the `P-Asserted-Identity` header of the delivered call.

  A gateway that has not asked for anything else reports `+{number}`,
  which is E.164. A format with no `{number}` states that same identity on
  every call, whoever called.
- `destination_format` (string, required)

  How this gateway formats the dialed number. In the template,
  `{number}` represents the number without its leading `+`. The result
  is placed before the `sip_uri` host. For example, `1234#{number}`
  formats `+31201234567` as
  `sip:1234#31201234567@pbx.example.com:5060`.

  A gateway that has not asked for anything else reports `+{number}`,
  which is E.164. A format with no `{number}` is dialed as it stands, so
  every number the trunk answers reaches that one number.
- `created_at` (string, required)
- `updated_at` (string, required)

## Related resources

- [Should I use a Bird SDK or call the API directly?](/explained/platform/should-i-use-an-sdk-or-call-the-api-directly) (answer)
- [Build your first integration](/learn/paths/integration) (course)
- [Send your first email](/docs/get-started/send-your-first-email) (docs)

[Get an implementation brief](/learn/workspace?topic=api-basics)