> ## Documentation Index > Fetch the complete documentation index at: https://docs.powerdialer.ai/llms.txt > Use this file to discover all available pages before exploring further. # Add a contact to a list > Attach an existing contact to a calling list without creating another contact record. Requires `lists:write` and `contacts:read`. Both the list and contact must be visible within the key's workspace and permitted owner scope; knowing their IDs alone does not grant access. Use numeric PowerDialer IDs for both path parameters and send no request body. The response is `{listId,contactId,member:true}`. Contact fields and ownership remain unchanged. For a new lead, create or upsert the contact first; for many rows, consider an asynchronous import instead. Persist an `Idempotency-Key` for the attachment and reuse the same request after a timeout. `404 not_found` can refer to either missing or inaccessible resource; check both IDs with permitted read endpoints. `403 insufficient_scope` requires both permissions. `409 idempotency_conflict` means the operation key was reused for another action. See [membership operations](/guides/contact-lists#list-membership). ## OpenAPI ````yaml /api/openapi.json put /lists/{id}/contacts/{contactId} openapi: 3.1.0 info: title: PowerDialer API v2 version: 2.0.0 description: >- Connect your CRM, sales workspace or reporting tools to PowerDialer using scoped API keys. Manage contacts and calling lists, read call evidence and analytics, and receive signed events. All example records and IDs are synthetic; replace them with values from your workspace. Shared-key v1 is retired. API availability was verified on 2026-10-08; see /availability for historical data coverage. Legacy outbound webhooks use a separate contract. servers: - url: https://api.migration.powerdialer.ai/api/public/v2 description: Production API v2; availability verified on 2026-10-08. security: - ApiKey: [] tags: - name: Authentication - name: Contacts - name: Calling lists - name: Imports - name: Calls - name: Synchronization - name: Analytics - name: Webhooks - name: Webhook deliveries - name: Incoming webhook payloads paths: /lists/{id}/contacts/{contactId}: put: tags: - Calling lists summary: Add a contact to a list description: >- Attach an existing contact to a calling list without creating another contact record. Requires `lists:write` and `contacts:read`. Both the list and contact must be visible within the key's workspace and permitted owner scope; knowing their IDs alone does not grant access. Use numeric PowerDialer IDs for both path parameters and send no request body. The response is `{listId,contactId,member:true}`. Contact fields and ownership remain unchanged. For a new lead, create or upsert the contact first; for many rows, consider an asynchronous import instead. Persist an `Idempotency-Key` for the attachment and reuse the same request after a timeout. `404 not_found` can refer to either missing or inaccessible resource; check both IDs with permitted read endpoints. `403 insufficient_scope` requires both permissions. `409 idempotency_conflict` means the operation key was reused for another action. See [membership operations](/guides/contact-lists#list-membership). operationId: putListsByIdContactsByContactid parameters: - name: id in: path required: true schema: type: integer minimum: 1 maximum: 2147483647 description: >- Numeric calling-list ID returned by POST /lists or GET /lists. The list must be visible to this credential. example: 456 - name: contactId in: path required: true schema: type: integer minimum: 1 maximum: 2147483647 description: >- Numeric PowerDialer contact ID from a contact read/write or import result. The contact must be visible to this credential. example: 123 - name: Idempotency-Key in: header required: true schema: type: string pattern: ^[A-Za-z0-9._:-]{1,200}$ description: >- Persist one key for this logical operation before sending it. Reuse the same value only with the same method, path and body after a timeout. A changed request returns 409 idempotency_conflict; a matching retry returns the original response. example: 9d6b623c-c132-4d2f-b8cf-7c65d4760dbe responses: '200': description: >- The contact is a member of the list, or the original successful attachment response was replayed. headers: X-Request-Id: schema: type: string format: uuid RateLimit-Limit: schema: type: integer RateLimit-Remaining: schema: type: integer Idempotency-Replayed: schema: type: string enum: - 'true' - 'false' content: application/json: schema: $ref: '#/components/schemas/Membership' example: listId: 456 contactId: 123 member: true default: description: >- Error. 400 invalid request; 401 invalid credential; 403 insufficient access; 404 not found; 409 state/idempotency conflict; 413 size limit; 422 verification failure; 429 rate limit (Retry-After seconds); 503 temporary service failure. headers: Retry-After: schema: type: integer X-Request-Id: schema: type: string format: uuid content: application/json: schema: $ref: '#/components/schemas/Error' example: error: code: invalid_api_key message: API key is invalid, expired or revoked requestId: 00000000-0000-4000-8000-000000000004 x-codeSamples: - lang: bash label: cURL source: >- # Replace example resource IDs and ownerId with values from your workspace. : "${POWERDIALER_API_KEY:?Set POWERDIALER_API_KEY to your scoped API key}" # Set this once per operation; reuse it with the same request after a timeout. : "${POWERDIALER_REQUEST_ID:?Set POWERDIALER_REQUEST_ID to a new UUID for this operation}" curl --request PUT \ --url 'https://api.migration.powerdialer.ai/api/public/v2/lists/456/contacts/123' \ --header "Authorization: Bearer $POWERDIALER_API_KEY" \ --header "Idempotency-Key: $POWERDIALER_REQUEST_ID" components: schemas: Membership: type: object properties: listId: type: integer description: Calling-list ID. contactId: type: integer description: Contact ID. member: type: boolean description: True after adding membership; false after removing it. required: - listId - contactId - member examples: - listId: 456 contactId: 123 member: true Error: type: object properties: error: type: object properties: code: type: string description: Stable machine-readable error code. message: type: string description: Human-readable explanation. requestId: type: string format: uuid description: Request identifier to include when investigating a failure. details: type: array items: type: object properties: path: type: string message: type: string required: - path - message description: Validation errors, when available. required: - code - message - requestId required: - error examples: - error: code: insufficient_scope message: Requires contacts:read requestId: 00000000-0000-4000-8000-000000000004 securitySchemes: ApiKey: type: http scheme: bearer bearerFormat: pd__. description: >- Issued in Developers. Workspace/owner/scopes come from credential, never acting-user headers. API keys cannot manage API credentials. ```` This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.