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

# Conversation behavior

## Docs

- [Variables](https://docs.vapi.ai/assistants/dynamic-variables.md): Personalize Vapi assistant prompts and messages with dynamic variables in double curly braces, setting values at call time through assistantOverrides.
- [Multilingual support](https://docs.vapi.ai/customization/multilingual.md): Configure multilingual voice AI agents with automatic language detection, cross-language conversation, and localized voices
- [Personalization with user information](https://docs.vapi.ai/assistants/personalization.md): Personalize Vapi conversations with customer-specific data your server supplies at call time, tailoring responses for support, account management, and more.
- [Voice formatting plan](https://docs.vapi.ai/assistants/voice-formatting-plan.md): Format Vapi LLM output for natural-sounding speech, expanding numbers, currency, and symbols so text-to-speech reads them clearly, enabled by default.
- [Flush syntax](https://docs.vapi.ai/assistants/flush-syntax.md): Force immediate voice transmission with VAPI's flush syntax for real-time interactions
- [Background messages](https://docs.vapi.ai/assistants/background-messages.md): Silently add information to a Vapi call's chat history without notifying the user, logging button presses, actions, or context updates during the conversation.
- [Idle messages](https://docs.vapi.ai/assistants/idle-messages.md): Keep users engaged during Vapi call pauses with idle messages that trigger on customer silence, using fixed text or model-generated prompts via assistant hooks.
- [Assistant hooks](https://docs.vapi.ai/assistants/assistant-hooks.md): Automate actions on Vapi call events like ending and speech interruptions, using assistant hooks to transfer calls, run functions, or send messages.
- [Call timeout settings](https://docs.vapi.ai/documentation/assistants/conversation-behavior/call-timeout-settings.md): Configure silence and maximum-duration timeouts for assistants, distinguish inactivity from total call duration, and troubleshoot timeout call endings.
- [Keypad input settings](https://docs.vapi.ai/documentation/assistants/conversation-behavior/keypad-input-settings.md): Keypad input settings let assistants collect caller-entered digits. Configure timeouts and delimiters for menus, codes, and account information during calls.
- [End call phrases](https://docs.vapi.ai/documentation/assistants/conversation-behavior/end-call-phrases.md): End call phrases let assistants end calls after saying configured text. Choose reliable phrases and prevent unintended transcript matches during calls.
- [Background speech denoising](https://docs.vapi.ai/documentation/assistants/conversation-behavior/background-speech-denoising.md): Filter out noise and background speech while users are talking
- [Pronunciation dictionaries](https://docs.vapi.ai/assistants/pronunciation-dictionaries.md): Control how a Vapi assistant pronounces specific words, names, and acronyms using pronunciation dictionaries with phoneme and alias rules by voice provider.
- [Email address reading](https://docs.vapi.ai/assistants/email-address-reading.md): Get a Vapi voice agent to collect, read back, and confirm email addresses clearly, using built-in TTS formatting, prompting, and confirmation techniques.