> ## Documentation Index
> Fetch the complete documentation index at: https://docs.agentline.cloud/llms.txt
> Use this file to discover all available pages before exploring further.

# Send Message

> Send an outbound SMS message from an AI agent's phone number.



## OpenAPI

````yaml /openapi.json post /v1/messages
openapi: 3.1.0
info:
  title: AgentLine
  description: >-
    AgentLine gives every AI agent a real phone number, a human-like voice, and
    the ability to make and receive calls and SMS autonomously. This SDK covers
    the core developer surface: agents, numbers, calls, messages, events,
    webhooks, billing, and voice.
  version: 0.3.0
  summary: Phone numbers, voice, and SMS for AI agents.
  contact:
    name: AgentLine
    url: https://agentline.cloud
  license:
    name: MIT
    url: https://opensource.org/license/mit
servers:
  - url: https://api.agentline.cloud
    description: Production
security:
  - API Key or OAuth: []
paths:
  /v1/messages:
    post:
      tags:
        - Messages
      summary: Send Message
      description: Send an outbound SMS message from an AI agent's phone number.
      operationId: send_sms
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/MessageSend'
      responses:
        '200':
          description: Successful Response
          content:
            application/json:
              schema: {}
        '422':
          description: Validation Error
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/HTTPValidationError'
      security:
        - API Key or OAuth: []
components:
  schemas:
    MessageSend:
      properties:
        agent_id:
          type: string
          title: Agent Id
          description: ID of the AI agent sending the SMS (e.g. 'agt_abc123')
        to_number:
          type: string
          title: To Number
          description: Destination phone number in E.164 format (e.g. '+12125551234')
        body:
          type: string
          title: Body
          description: SMS message text content
        media_url:
          anyOf:
            - type: string
            - type: 'null'
          title: Media Url
          description: URL of media to attach (MMS)
        from_number_id:
          anyOf:
            - type: string
            - type: 'null'
          title: From Number Id
          description: >-
            Specific phone number ID to send from; defaults to the agent's
            assigned number
      type: object
      required:
        - agent_id
        - to_number
        - body
      title: MessageSend
    HTTPValidationError:
      properties:
        detail:
          items:
            $ref: '#/components/schemas/ValidationError'
          type: array
          title: Detail
      type: object
      title: HTTPValidationError
    ValidationError:
      properties:
        loc:
          items:
            anyOf:
              - type: string
              - type: integer
          type: array
          title: Location
        msg:
          type: string
          title: Message
        type:
          type: string
          title: Error Type
        input:
          title: Input
        ctx:
          type: object
          title: Context
      type: object
      required:
        - loc
        - msg
        - type
      title: ValidationError
  securitySchemes:
    API Key or OAuth:
      type: http
      description: >-
        AgentLine API key. Get one via the email OTP flow (POST /v1/auth/otp
        then POST /v1/auth/verify). Pass as: Authorization: Bearer sk_live_...
      scheme: bearer
      bearerFormat: API key (sk_live_...)
      x-fern-bearer:
        name: apiKey
        env: AGENTLINE_API_KEY

````