Bolna Voice AI automatically detects the language your callers speak and switches system messages to match. No manual intervention needed. The agent analyzes the conversation and delivers the right message in the right language.Documentation Index
Fetch the complete documentation index at: https://www.bolna.ai/docs/llms.txt
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User Online Check
“Are you still there?” plays in the caller’s detected language
Call Hangup
Farewell message delivered in the detected language
Tool Call Wait
“Please wait” messages during API calls adapt to the language
How Detection Works
Conversation Begins
The agent starts in the primary language configured in the Audio Tab.
Language Analysis
After 3 conversation turns, Bolna analyzes the caller’s transcripts to identify the dominant language being spoken.
Detection waits for 3 turns to gather enough context for accurate identification. This keeps it fast while avoiding false matches early in the call.
Supported Message Types
User Online Check Message
When the agent checks if a caller is still on the line after a period of silence, it sends a configurable message. Add variants in multiple languages and Bolna picks the right one automatically.
Call Hangup Message
When the agent ends a call, it delivers a closing message. Configure multilingual variants so callers hear a natural farewell in their language.
Function Tool Call Messages
When the agent executes a tool or API call, it plays a brief “please wait” message. This message can also be configured per language.
Fallback Behavior
When selecting a message, Bolna follows a three-step fallback:| Priority | What happens |
|---|---|
| 1. Detected language | Uses the message in the caller’s detected language |
| 2. English | Falls back to the en variant if the detected language is not configured |
| 3. First available | Uses the first language in the configuration if neither is found |
Supported Languages
Auto-detection supports all languages available in Bolna, identified by their ISO 639-1 codes.| Code | Language | Code | Language | Code | Language |
|---|---|---|---|---|---|
en | English | hi | Hindi | bn | Bengali |
ta | Tamil | te | Telugu | mr | Marathi |
gu | Gujarati | kn | Kannada | ml | Malayalam |
pa | Punjabi | ur | Urdu | as | Assamese |
For the full list of supported languages, see the Multilingual Support guide.
Best Practices
Consistent Coverage
Add message variants for every language your agent supports. Gaps lead to unexpected fallbacks.
Culturally Appropriate
Write messages that feel natural in each language. Avoid direct translations.
Native Script
Always use the language’s native script. “धन्यवाद” not “Dhanyavaad”.
Test with Speakers
Verify messages sound natural by testing with native speakers of each language.
Next Steps
Multilingual Support
Full guide to setting up multilingual agents
Non-English Prompts
Best practices for writing prompts in native scripts
Custom Function Calls
Configure pre-call messages for API tools
Engine Tab
Configure user online detection and timeouts

