How Multilingual Agents Work
A multilingual agent can understand and respond in multiple languages within a single call. Here is how the pieces fit together:Per-Language Prompts
Each language gets its own prompt tab. Write a dedicated prompt for every language your agent supports.
Language Switching
A shared instruction field tells the agent when to switch languages mid-call.
Setting Up Languages
Set a Primary Language
Click the crown icon next to any language to make it primary. The primary language is what the agent starts every conversation in.
Write a Prompt for Each Language
In the Agent Tab, select each language tab and write its prompt. The agent activates the matching prompt when speaking in that language.
Configure Handoff Messages
In the Advanced Settings for each language, set a Handoff Message that plays when the agent transitions away from that language.
Language Switching
The Language Switching Instructions field in the Agent Tab is a single shared field that applies to all languages. It tells the agent when and how to switch languages during a call.| What to include | Example |
|---|---|
| Trigger conditions | ”Switch to Hindi if the user speaks in Hindi” |
| Fallback behavior | ”Fall back to English if the language is unsupported” |
| Default rule | ”Respond in the language the user is currently using” |
Write these once. They apply across all languages automatically.
Auto-Switching System Messages
Beyond prompt-level switching, Bolna can also auto-detect the caller’s language and switch system messages to match. This works for:User Online Check
“Are you still there?” adapts to the caller’s language
Hangup Message
Farewell message plays in the detected language
Tool Call Messages
“Please wait” messages during API calls match the language
Per-Language Configuration
Each language you add gets its own independent configuration:
| What | Where | Scope |
|---|---|---|
| Prompt | Agent Tab, language tabs | Per language |
| Agent Name | Agent Tab, Advanced Settings | Per language |
| Handoff Message | Agent Tab, Advanced Settings | Per language |
| Language Switching Instructions | Agent Tab | Shared across all |
| Text-to-Speech | Audio Tab | Per language |
| Speech-to-Text | Audio Tab | Per language |
Settings are independent per language. The Agent Name, Handoff Message, STT provider, and TTS provider for Hindi do not affect English.
Supported Languages
| Language | Code |
|---|---|
| English | en |
| Hindi | hi |
| Bengali | bn |
| Assamese | as |
| French | fr |
| Gujarati | gu |
| Indonesian | id |
| Kannada | kn |
| Malay | ms |
| Malayalam | ml |
| Marathi | mr |
| Odia | od |
| Punjabi | pa |
| Spanish | es |
| Tamil | ta |
| Telugu | te |
| Urdu | ur |
| Dutch | nl |
Writing Effective Multilingual Prompts
Use Native Script
Write prompts in the language’s native script, not phonetic English. “नमस्ते” not “Namaste”.
Include Accented Characters
Use proper accents for European languages. “Cómo estás?” not “Como estas?”
Examples: Correct vs Incorrect Prompts
Examples: Correct vs Incorrect Prompts
Hindi
- Incorrect: “Namaste! Aap kaise ho?”
- Correct: “नमस्ते! आप कैसे हैं?”
- Incorrect: “Hola! Como estas?”
- Correct: “¡Hola! ¿Cómo estás?”
- Incorrect: “Bonjour! Comment ca va?”
- Correct: “Bonjour ! Comment ça va ?”
Multilingual Knowledge Bases
If your agent uses knowledge bases with non-English documents, enable multilingual support when creating the knowledge base. This supports 100+ languages, allowing your agent to retrieve information regardless of document or query language.Learn more in the Knowledge Base documentation.
Next Steps
Agent Tab
Configure per-language prompts and handoff messages
Audio Tab
Set up languages, voices, and transcription
Auto-Switch Languages
Auto-detect and switch system messages by language
Non-English Prompts Guide
Best practices for writing multilingual prompts