### Answer You cannot dynamically change the

language

setting mid-call. The language setting determines what language the speech recognition operates in and is set at the agent level. [(1) ]() However, there are a couple of approaches you can use: Option 1: Use Multilingual Mode Set your agent's language to

multi

for multilingual support. [(1) ]() [(2) ]() The multilingual option supports seamlessly switching between English, Spanish, French, German, Hindi, Russian, Portuguese, Japanese, Italian, Dutch, and Chinese. [(3) ]() [(4) ]() Option 2: Agent Swap If you want dedicated language-optimized agents, you can use agent swap to switch to a Chinese-speaking agent when the caller selects that option. [(5) ]() *Option 3: Prompt-Based Approach (for Conversation Flow) * If using Conversation Flow with multilingual mode, you can extract the user's language preference into a dynamic variable (e.g.,

{{user_language}}

) and include instructions in each node's prompt like: > "Always speak in {{user_language}} throughout this node." Note: The language setting itself will not enforce the agent to generate responses in a certain language—you need to set that in the prompt. [(1) ]()

​ To learn more, see the sources I considered: [[1] Set language for your agent](https://docs.retellai.com/agent/language) [[2] Create Voice Agent](https://docs.retellai.com/api-references/create-agent) [[3] OpenAI 4.1, Version Control, and More Languages Support](https://www.retellai.com/changelog/openai-4-1-version-control-and-more-languages-support) [[4] Platform Changelogs | Retell AI](https://www.retellai.com/changelog) [[5] Language Switching](https://discord.com/channels/1186424376300679209/1397465772074467338) ​

Feel free to tag @AI Evy with additional questions. I also appreciate feedback, it helps me improve.

### Answer For multi-prompt agents, you can use the Agent Transfer tool (also known as Agent Swap) to switch to a different agent mid-call. [(1) ]() Steps to set up Agent Transfer in a multi-prompt agent: 1. Add Agent Transfer Tool – Click "Add" in the tools section and select "Agent Transfer" from the dropdown menu. 2. Configure Details – Set the following: - **Transfer agent**: the ID and version of the agent to transfer to (e.g., your Chinese-language agent) . You can select the latest version as well. - **Speak during execution and messages**: whether the agent should speak something while performing the transfer. - **Post call analysis setting**: choose whether to extract dynamic variables for only the transferred agent or both agents. 3. Update the Prompt – Add instructions in your prompt telling the agent when to trigger the transfer. For example: > "If the user asks to speak in Chinese, use the agent_transfer tool to transfer to the Chinese Agent." 4. Test and Debug – You can test agent transfer in both web call and playground. Benefits of Agent Transfer over Call Transfer: - Lower latency (near-instant transition) - Better reliability (no new phone call needed) - The destination agent has access to the full conversation history - No separate phone numbers needed for transferred agents

​ To learn more, see the sources I considered: [[1] Agent Transfer](https://docs.retellai.com/build/single-multi-prompt/transfer-agent) ​

Feel free to tag @AI Evy with additional questions. I also appreciate feedback, it helps me improve.