AT&T In-App Messaging API

openapi: 3.0.3
info:
  title: AT&T In-App Messaging API
  description: >-
    A messaging API enabling applications to send, receive, update, and delete
    MMS and SMS messages on behalf of AT&T users with explicit OAuth consent.
    Supports messages to phone numbers, short codes, and email addresses across
    AT&T and other carriers with full inbox management and delta synchronization.
  version: '2.0'
  contact:
    url: https://developer.att.com/support
  termsOfService: https://www.att.com/gen/general?pid=11561
  x-generated-from: documentation
  x-last-validated: '2026-04-19'
servers:
  - url: https://api.att.com
    description: AT&T API Gateway
paths:
  /myMessages/v2/messages:
    post:
      operationId: sendMessage
      summary: AT&T Send MMS or SMS Message
      description: >-
        Send an MMS or SMS message on behalf of the authenticated user to one or
        more recipients. Supports SMS (up to 160 characters) and MMS (up to 1 MB
        with up to 21 attachments). Supports cross-carrier delivery and group messaging.
      tags:
        - Messages
      security:
        - oauth2: [IMMN]
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/SendMessageRequest'
            examples:
              SendMessageRequestExample:
                summary: Default sendMessage request
                x-microcks-default: true
                value:
                  messageRequest:
                    addresses:
                      - tel:+12125551234
                    text: Hello from the AT&T In-App Messaging API!
                    subject: Greeting
      responses:
        '201':
          description: Message successfully sent
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/SendMessageResponse'
              examples:
                SendMessage201Example:
                  summary: Default sendMessage 201 response
                  x-microcks-default: true
                  value:
                    id: msg-500123
                    resourceURL: https://api.att.com/myMessages/v2/messages/msg-500123
        '400':
          description: Bad request - invalid parameters
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ErrorResponse'
        '401':
          description: Unauthorized - invalid or expired token
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ErrorResponse'
      x-microcks-operation:
        delay: 0
        dispatcher: FALLBACK
    get:
      operationId: listMessages
      summary: AT&T List Messages
      description: >-
        Retrieve a list of messages from the authenticated user's inbox. Supports
        filtering by message type, read status, and time range. Returns message
        metadata without the full message content.
      tags:
        - Messages
      security:
        - oauth2: [MIM]
      parameters:
        - name: limit
          in: query
          required: false
          description: Maximum number of messages to return
          schema:
            type: integer
            minimum: 1
            maximum: 500
            example: 50
        - name: offset
          in: query
          required: false
          description: Number of messages to skip for pagination
          schema:
            type: integer
            minimum: 0
            example: 0
        - name: isUnread
          in: query
          required: false
          description: Filter to only unread messages when true
          schema:
            type: boolean
            example: true
      responses:
        '200':
          description: Message list successfully retrieved
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/MessageListResponse'
              examples:
                ListMessages200Example:
                  summary: Default listMessages 200 response
                  x-microcks-default: true
                  value:
                    messageResultSet:
                      messages:
                        - messageId: msg-500123
                          from: tel:+12125551234
                          recipients:
                            - tel:+12125559999
                          isUnread: false
                          isIncoming: true
                          type: TEXT
                          typeCode: '1'
                          timeStamp: '2026-04-19T14:30:00Z'
                      totalCount: 1
                      offset: 0
                      limit: 50
        '401':
          description: Unauthorized
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ErrorResponse'
      x-microcks-operation:
        delay: 0
        dispatcher: FALLBACK
  /myMessages/v2/messages/{messageId}:
    get:
      operationId: getMessage
      summary: AT&T Get Message Details
      description: >-
        Retrieve the full details and content of a specific message by its ID,
        including text content, attachments, sender, recipients, and metadata.
      tags:
        - Messages
      security:
        - oauth2: [MIM]
      parameters:
        - name: messageId
          in: path
          required: true
          description: Unique message identifier
          schema:
            type: string
            example: msg-500123
      responses:
        '200':
          description: Message details successfully retrieved
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/MessageDetail'
              examples:
                GetMessage200Example:
                  summary: Default getMessage 200 response
                  x-microcks-default: true
                  value:
                    message:
                      messageId: msg-500123
                      from: tel:+12125551234
                      recipients:
                        - tel:+12125559999
                      text: Hello from the AT&T In-App Messaging API!
                      subject: Greeting
                      isUnread: false
                      isIncoming: true
                      type: TEXT
                      typeCode: '1'
                      timeStamp: '2026-04-19T14:30:00Z'
        '404':
          description: Message not found
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ErrorResponse'
        '401':
          description: Unauthorized
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ErrorResponse'
      x-microcks-operation:
        delay: 0
        dispatcher: FALLBACK
    put:
      operationId: updateMessage
      summary: AT&T Update Message Properties
      description: >-
        Update the properties of a message, such as marking it as read or unread.
        Only the isUnread field can be modified.
      tags:
        - Messages
      security:
        - oauth2: [MIM]
      parameters:
        - name: messageId
          in: path
          required: true
          description: Unique message identifier
          schema:
            type: string
            example: msg-500123
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/UpdateMessageRequest'
            examples:
              UpdateMessageRequestExample:
                summary: Default updateMessage request
                x-microcks-default: true
                value:
                  message:
                    isUnread: false
      responses:
        '200':
          description: Message successfully updated
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/UpdateMessageResponse'
              examples:
                UpdateMessage200Example:
                  summary: Default updateMessage 200 response
                  x-microcks-default: true
                  value:
                    id: msg-500123
        '404':
          description: Message not found
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ErrorResponse'
        '401':
          description: Unauthorized
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ErrorResponse'
      x-microcks-operation:
        delay: 0
        dispatcher: FALLBACK
    delete:
      operationId: deleteMessage
      summary: AT&T Delete Message
      description: >-
        Permanently delete a specific message from the user's inbox by its ID.
        This action cannot be undone.
      tags:
        - Messages
      security:
        - oauth2: [MIM]
      parameters:
        - name: messageId
          in: path
          required: true
          description: Unique message identifier
          schema:
            type: string
            example: msg-500123
      responses:
        '204':
          description: Message successfully deleted
        '404':
          description: Message not found
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ErrorResponse'
        '401':
          description: Unauthorized
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ErrorResponse'
      x-microcks-operation:
        delay: 0
        dispatcher: FALLBACK
  /myMessages/v2/messages/index:
    post:
      operationId: createMessageIndex
      summary: AT&T Create Message Index Cache
      description: >-
        Create or refresh the server-side message index cache for the authenticated
        user. This index must be created before delta synchronization can be used.
        Returns a state object for subsequent delta sync calls.
      tags:
        - Inbox Management
      security:
        - oauth2: [MIM]
      responses:
        '200':
          description: Message index successfully created
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/MessageIndexResponse'
              examples:
                CreateMessageIndex200Example:
                  summary: Default createMessageIndex 200 response
                  x-microcks-default: true
                  value:
                    messageIndexInfo:
                      state: state-a1b2c3d4
                      status: INITIALIZED
        '401':
          description: Unauthorized
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ErrorResponse'
      x-microcks-operation:
        delay: 0
        dispatcher: FALLBACK
  /myMessages/v2/delta:
    get:
      operationId: getInboxDelta
      summary: AT&T Get Inbox Changes (Delta Sync)
      description: >-
        Retrieve changes to the user's inbox since the last synchronization using
        a state token. Returns added, updated, and deleted messages since the
        previous state. Requires a message index to be created first.
      tags:
        - Inbox Management
      security:
        - oauth2: [MIM]
      parameters:
        - name: state
          in: query
          required: true
          description: State token from the previous delta sync or index creation
          schema:
            type: string
            example: state-a1b2c3d4
      responses:
        '200':
          description: Delta changes successfully retrieved
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/DeltaResponse'
              examples:
                GetInboxDelta200Example:
                  summary: Default getInboxDelta 200 response
                  x-microcks-default: true
                  value:
                    deltaResponse:
                      addedMessages:
                        - messageId: msg-500789
                          from: tel:+12125551234
                          isUnread: true
                          type: TEXT
                          timeStamp: '2026-04-19T15:00:00Z'
                      updatedMessages: []
                      deletedMessages: []
                      state: state-e5f6g7h8
        '400':
          description: Bad request - invalid state token
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ErrorResponse'
        '401':
          description: Unauthorized
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ErrorResponse'
      x-microcks-operation:
        delay: 0
        dispatcher: FALLBACK
components:
  securitySchemes:
    oauth2:
      type: oauth2
      description: AT&T OAuth 2.0 with user consent via authorization code flow
      flows:
        authorizationCode:
          authorizationUrl: https://api.att.com/oauth/v4/authorize
          tokenUrl: https://api.att.com/oauth/v4/token
          scopes:
            IMMN: Send Message - send MMS and SMS messages on behalf of user
            MIM: Message Inbox Management - read, update, and delete messages
  schemas:
    SendMessageRequest:
      type: object
      required:
        - messageRequest
      properties:
        messageRequest:
          type: object
          required:
            - addresses
          properties:
            addresses:
              type: array
              description: List of recipient phone numbers or email addresses
              items:
                type: string
              example:
                - tel:+12125551234
            text:
              type: string
              description: SMS text content (up to 160 chars for SMS, longer for MMS)
              example: Hello from the AT&T In-App Messaging API!
            subject:
              type: string
              description: Subject line (MMS only)
              example: Greeting
            group:
              type: boolean
              description: If true, send as a group message
              example: false
    SendMessageResponse:
      type: object
      properties:
        id:
          type: string
          description: Unique identifier for the sent message
          example: msg-500123
        resourceURL:
          type: string
          format: uri
          description: URL to access the message resource
          example: https://api.att.com/myMessages/v2/messages/msg-500123
    MessageSummary:
      type: object
      properties:
        messageId:
          type: string
          description: Unique message identifier
          example: msg-500123
        from:
          type: string
          description: Sender address (phone number or email)
          example: tel:+12125551234
        recipients:
          type: array
          description: List of recipient addresses
          items:
            type: string
          example:
            - tel:+12125559999
        isUnread:
          type: boolean
          description: Whether the message has been read
          example: false
        isIncoming:
          type: boolean
          description: True if message was received, false if sent
          example: true
        type:
          type: string
          description: Message type
          enum:
            - TEXT
            - MMS
          example: TEXT
        typeCode:
          type: string
          description: Numeric type code
          example: '1'
        timeStamp:
          type: string
          format: date-time
          description: Date and time the message was sent or received
          example: '2026-04-19T14:30:00Z'
    MessageDetail:
      type: object
      properties:
        message:
          allOf:
            - $ref: '#/components/schemas/MessageSummary'
            - type: object
              properties:
                text:
                  type: string
                  description: Full text content of the message
                  example: Hello from the AT&T In-App Messaging API!
                subject:
                  type: string
                  description: Subject line (MMS only)
                  example: Greeting
    MessageListResponse:
      type: object
      properties:
        messageResultSet:
          type: object
          properties:
            messages:
              type: array
              items:
                $ref: '#/components/schemas/MessageSummary'
            totalCount:
              type: integer
              description: Total number of messages matching the query
              example: 1
            offset:
              type: integer
              description: Current pagination offset
              example: 0
            limit:
              type: integer
              description: Maximum messages per page
              example: 50
    UpdateMessageRequest:
      type: object
      properties:
        message:
          type: object
          properties:
            isUnread:
              type: boolean
              description: Updated read status of the message
              example: false
    UpdateMessageResponse:
      type: object
      properties:
        id:
          type: string
          description: ID of the updated message
          example: msg-500123
    MessageIndexResponse:
      type: object
      properties:
        messageIndexInfo:
          type: object
          properties:
            state:
              type: string
              description: State token to use for delta synchronization
              example: state-a1b2c3d4
            status:
              type: string
              description: Index creation status
              enum:
                - INITIALIZED
                - IN_PROGRESS
                - COMPLETE
              example: INITIALIZED
    DeltaResponse:
      type: object
      properties:
        deltaResponse:
          type: object
          properties:
            addedMessages:
              type: array
              description: Messages added since last sync
              items:
                $ref: '#/components/schemas/MessageSummary'
            updatedMessages:
              type: array
              description: Messages updated since last sync
              items:
                $ref: '#/components/schemas/MessageSummary'
            deletedMessages:
              type: array
              description: Message IDs deleted since last sync
              items:
                type: string
              example: []
            state:
              type: string
              description: New state token for next delta sync call
              example: state-e5f6g7h8
    ErrorResponse:
      type: object
      properties:
        RequestError:
          type: object
          properties:
            ServiceException:
              type: object
              properties:
                MessageId:
                  type: string
                  description: Error message ID
                  example: SVC0002
                Text:
                  type: string
                  description: Human-readable error description
                  example: Invalid input value for message part
                Variables:
                  type: string
                  description: Additional error context
                  example: address