> ## Documentation Index > Fetch the complete documentation index at: https://docs.zavu.dev/llms.txt > Use this file to discover all available pages before exploring further. # Connect a sender to an agent > Make the agent answer on this sender. An agent can serve several senders; a sender answers with at most one agent, so connecting one that is already in use returns `400` naming the agent that holds it. ## OpenAPI ````yaml /openapi.json post /v1/agents/{agentId}/senders openapi: 3.0.3 info: title: Zavu Unified Messaging Layer API version: 0.2.0 description: > Unified multi-channel messaging API for Zavu. Supported channels: - **SMS**: Simple text messages - **WhatsApp**: Rich messaging with media, buttons, lists, CTA URL buttons, and templates - **Telegram**: Bot messaging with text, media, and interactive elements - **Email**: Transactional emails via Amazon SES Design goals: - Simple `send()` entrypoint for developers - Project-level authentication via Bearer token - Support for all WhatsApp message types (text, image, video, audio, document, sticker, location, contact, buttons, list, cta_url, reaction, template) - If a non-text message type is sent, WhatsApp channel is used automatically - 24-hour WhatsApp conversation window enforcement - Universal `to` field accepts phone numbers (E.164), email addresses, or numeric chat IDs (Telegram/Instagram/Messenger) servers: - url: https://api.zavu.dev security: - bearerAuth: [] paths: /v1/agents/{agentId}/senders: post: tags: - Agents summary: Connect a sender to an agent description: >- Make the agent answer on this sender. An agent can serve several senders; a sender answers with at most one agent, so connecting one that is already in use returns `400` naming the agent that holds it. operationId: attachAgentSender parameters: - $ref: '#/components/parameters/AgentIdParam' requestBody: required: true content: application/json: schema: type: object required: - senderId properties: senderId: type: string description: Sender to connect. responses: '201': description: Sender connected. content: application/json: schema: type: object required: - agent properties: agent: $ref: '#/components/schemas/Agent' '400': description: senderId missing, or the sender already answers with another agent. content: application/json: schema: $ref: '#/components/schemas/Error' '401': description: Unauthorized. content: application/json: schema: $ref: '#/components/schemas/Error' '404': description: Agent or sender not found. content: application/json: schema: $ref: '#/components/schemas/Error' security: - bearerAuth: [] components: parameters: AgentIdParam: name: agentId in: path required: true description: Agent ID. schema: type: string schemas: Agent: type: object description: AI Agent configuration for a sender. required: - id - senderId - name - enabled - provider - model - systemPrompt - createdAt - updatedAt properties: id: type: string example: agent_abc123 senderId: type: string example: sender_12345 name: type: string example: Customer Support Agent enabled: type: boolean description: Whether the agent is active. provider: $ref: '#/components/schemas/AgentProvider' model: type: string description: Model ID (e.g., gpt-4o-mini, claude-3-5-sonnet). example: gpt-4o-mini systemPrompt: type: string description: System prompt for the agent. contextWindowMessages: type: integer description: Number of previous messages to include as context. default: 10 includeContactMetadata: type: boolean description: Whether to include contact metadata in context. default: true maxTokens: type: integer description: Maximum tokens for LLM response. nullable: true temperature: type: number description: LLM temperature (0-2). nullable: true triggerOnChannels: type: array items: type: string description: Channels that trigger the agent. example: - sms - whatsapp triggerOnMessageTypes: type: array items: type: string description: Message types that trigger the agent. example: - text stats: type: object properties: totalInvocations: type: integer totalTokensUsed: type: integer totalCost: type: number description: Total cost in USD. createdAt: type: string format: date-time updatedAt: type: string format: date-time voice: $ref: '#/components/schemas/AgentVoiceConfig' description: >- Voice Agent configuration. When present and enabled, the agent can answer inbound phone calls and place outbound calls with Zavu's managed voice pipeline. Requires the Voice Agents feature to be enabled for your team. senderIds: type: array items: type: string description: >- Senders this agent answers on. An agent can serve several; `senderId` remains the primary one, for compatibility. Error: type: object required: - code - message properties: code: type: string example: invalid_request message: type: string example: Phone number is invalid details: type: object additionalProperties: true AgentProvider: type: string description: LLM provider for the AI agent. enum: - openai - anthropic - google - mistral - zavu AgentVoiceConfig: type: object description: >- Voice Agent configuration on a sender's AI agent. Controls how the agent behaves on inbound and outbound phone calls through Zavu's managed voice pipeline (speech recognition, the agent's LLM, and speech synthesis, with real-time interruption handling). Requires the Voice Agents feature to be enabled for your team. required: - enabled properties: enabled: type: boolean description: >- Whether the agent handles voice calls. When false, the sender's number is not answered by the voice agent and outbound calls are rejected. greeting: type: string description: >- Opening line the agent speaks when the call connects. If omitted, the agent waits for the caller to speak first. maxLength: 1000 example: Hi, thanks for calling Acme. How can I help you today? greetings: type: object additionalProperties: type: string description: >- Greeting per language, keyed by language code. Used when the caller's language differs from the one `greeting` is written in. example: es: Hola, soy Atlas. Preguntame lo que quieras. language: type: string description: >- BCP-47 language code used for both speech recognition and speech synthesis (e.g. `en`, `es`, `pt-BR`). Auto-detected from the recipient when omitted. example: en model: type: string description: >- Model that runs the conversation, co-located in the voice network for lowest latency. Independent of the model used for text messaging. Derived from the agent's text model when omitted. example: openai/gpt-4o sttProvider: type: string description: Speech-recognition provider. Uses the default when omitted. sttModel: type: string description: Speech-recognition model. Uses the default when omitted. ttsProvider: type: string description: Speech-synthesis provider. Uses the default when omitted. ttsVoiceId: type: string description: >- Identifier of the synthesized voice that speaks. Choose from the voices available in the dashboard. Uses a neutral default when omitted. example: aria voiceSpeed: type: number description: >- Speech rate. 1.0 is natural. Only honoured by voices that support rate control; ignored by the others. minimum: 0.5 maximum: 1.5 default: 1 interruptible: type: boolean description: >- Whether the caller can interrupt the agent while it is speaking (barge-in). When true, the agent stops talking as soon as the caller starts. default: true maxCallDurationMinutes: type: integer description: >- Hard limit on call length in minutes. The call ends automatically when reached. minimum: 1 maximum: 120 default: 15 maxIdleSeconds: type: integer description: How long the agent waits during silence before ending the call. minimum: 5 maximum: 300 default: 30 recordCalls: type: boolean description: Whether the call audio is recorded. voicemailAction: type: string description: >- What the agent does when an answering machine or voicemail is detected on an outbound call. enum: - hangup - leave_message default: hangup voicemailMessage: type: string description: >- Message spoken when `voicemailAction` is `leave_message`. Falls back to `greeting` when omitted. maxLength: 1000 transferPhoneNumber: type: string description: >- E.164 phone number the agent can transfer the call to. When set, the agent is given a transfer tool it can use to hand the call to a human. example: '+14155551234' securitySchemes: bearerAuth: type: http scheme: bearer bearerFormat: JWT ````