Dear VAPI Team, My name is Timo Verbeek, and I am the GenAI Specialist @ the Generative AI team at Zonneplan (Dutch Energy Company). For your reference, we are working within the VAPI account associated with development@zonneplan.nl . This is our best current voicebot in your platform: https://dashboard.vapi.ai/assistants/0f676008-113b-42f0-bd6c-f8759f92e839 We are in the final stages of launching our AI voicebot and have encountered the following technical issues: 3. Handoff to agent error: When attempting to configure a handoff to an assistant, we receive the error message: "invalid destination 'assistant not found'". Could you please clarify what this error means and how we can fix it? 4. Handoff message language: The handoff message initiated by the tool call that is heard by the human agent is currently only available in English. Is it possible to localize this message into Dutch? If we use a Dutch summary the voicebot is not able to pronounce things. 5. Static IP addresses for LiteLLM: To finalize our LiteLLM integration, we need to whitelist your servers. Could you please provide us with the static IP addresses we should use for this? As we are planning to scale our usage of VAPI significantly, we are happy to schedule a brief introductory call if your team is interested in learning more about our project. Thank you for your time and support. Kind regards, Timo Verbeek GenAI Specialist

Hi Timo V, Regarding the issues you're facing with handoffs and message localization: 1. **Handoff to Agent Error**: The error message "invalid destination 'assistant not found'" suggests there might be an issue with the assistant ID or its configuration. Please ensure the

assistantId

or

assistantName

is correct. You might also want to check if the assistant is properly configured and available for the handoff. More details on configuration can be found [here](https://docs.vapi.ai/changelog/2025/8/14). 2. **Handoff Message Language**: Currently, handoff messages are only available in English. If you want to implement a Dutch summary, consider creating a custom message in your workflow that gets triggered during the handoff. 3. **Static IP Addresses for LiteLLM**: We don't have static IP addresses specifically listed. For whitelisting purposes, you might consider reaching out through your enterprise support channel for specific network configurations. If you need further assistance, feel free to ask.