---
title: "Create number group membership"
method: POST
path: "/api/relay/rest/number_groups/{NumberGroupId}/number_group_memberships"
tags: ["Number Group Membership"]
---

# Create number group membership

`POST /api/relay/rest/number_groups/{NumberGroupId}/number_group_memberships`

## Request

- Base URL: `https://{Your_Space_Name}.signalwire.com`
- URL: `https://{Your_Space_Name}.signalwire.com/api/relay/rest/number_groups/{NumberGroupId}/number_group_memberships`
- Auth: HTTP basic

Adds one project-owned phone number to a Number Group by phone-number ID. Use it to build or expand a sender pool after creating the group; this operation does not purchase or import the number. A phone number can belong to more than one group.

#### Permissions

The API token used to authenticate must have the following scope(s) enabled to make a successful request: _Numbers_.

[Learn more about API scopes](/docs/platform/your-signalwire-api-space).

## Path parameters

- `NumberGroupId` string, uuid, required: Universal Unique Identifier.

## Request body

- AddNumberGroupMembershipRequest: Request body for adding a phone number to a number group.
  - `phone_number_id` string, uuid, required: Universal Unique Identifier.

## Response `200`

The request has succeeded.

- NumberGroupMembershipResponse: Response containing a single number group membership.
  - `id` string, uuid, required: Universal Unique Identifier.
  - `number_group_id` string, uuid, required: Universal Unique Identifier.
  - `phone_number` MembershipPhoneNumber, required: Phone number representation within a membership.
    - `id` string, uuid: Universal Unique Identifier.
    - `name` string: The name given to the phone number.
    - `number` string: The phone number in E.164 format.
    - `capabilities` string[]: The capabilities of the phone number.
  - `created_at` string, required: The date and time when the membership was created.
  - `updated_at` string, required: The date and time when the membership was last updated.

## Other responses

- `401`: Access is unauthorized.
- `404`: The server cannot find the requested resource.
- `422`: The request failed validation. See errors for details.
- `500`: An internal server error occurred.

---

[API](https://skmtc.dev/signalwire/apis/signalwire-rest-api.md) - [All operations](https://skmtc.dev/signalwire/apis/signalwire-rest-api/llms.txt) - [OpenAPI document](https://skmtc.dev/signalwire/apis/signalwire-rest-api/revisions/7307749294e0?raw)