> For clean Markdown of any page, append .md to the page URL.
> For a complete documentation index, see https://docs.vapi.ai/llms.txt.
> For AI client integration (Claude Code, Cursor, etc.), connect to the MCP server at https://docs.vapi.ai/_mcp/server.

# Chat Transport & SMS Integration

1. **Twilio SMS Transport**: Send chat responses directly via SMS using [`TwilioSMSChatTransport`](https://api.vapi.ai/api#:~:text=TwilioSMSChatTransport) in [`CreateChatDTO.transport`](https://api.vapi.ai/api#:~:text=CreateChatDTO.transport). This enables programmatic SMS conversations with your voice assistants, bridging the gap between voice and text communication.

2. **SMS Session Management**: Create new sessions automatically when using SMS transport by providing:
   * `customer`: Customer information for SMS delivery
   * `phoneNumberId`: SMS-enabled phone number from your organization
   * Automatic session creation when both fields are provided

3. **LLM-Generated vs Direct SMS**: Control message processing with [`TwilioSMSChatTransport.useLLMGeneratedMessageForOutbound`](https://api.vapi.ai/api#:~:text=TwilioSMSChatTransport.useLLMGeneratedMessageForOutbound):
   * `true` (default): Input processed by assistant for intelligent responses
   * `false`: Direct message forwarding without LLM processing for notifications and alerts

4. **Enhanced Chat Creation**: [`CreateChatDTO`](https://api.vapi.ai/api#:~:text=CreateChatDTO) now supports sophisticated session management:
   * `transport`: SMS delivery configuration
   * `sessionId`: Use existing session data
   * Mutual exclusivity between `sessionId` and transport fields for clear session boundaries

5. **OpenAI Responses Integration**: Streamlined chat processing with [`OpenAIResponsesRequest`](https://api.vapi.ai/api#:~:text=OpenAIResponsesRequest) supporting the same transport and squad integration features for consistent API experience.

6. **Cross-Platform Continuity**: Seamlessly transition between voice calls and SMS conversations within the same session, maintaining context and conversation history across communication channels.

> **Info**
>
> SMS transport requires SMS-enabled phone numbers in your organization. The phone number must support SMS functionality and belong to your account for successful message delivery.

## SMS Communication Features

#### Bidirectional SMS

Send and receive SMS messages through your voice assistant, enabling text-based interactions alongside voice conversations.

#### Smart Processing

Choose between AI-processed responses and direct message forwarding based on your use case requirements.

#### Session Continuity

Maintain conversation context across SMS and voice interactions within unified sessions for seamless user experiences.

#### Automated Management

Automatic session creation and management when using transport fields, simplifying SMS conversation setup.