I am new to Vapi as well but I think Vapi have native support for this. You simply need to use the tool "Transfer Call" in your assistant. https://cdn.discordapp.com/attachments/1211484481848873020/1357528523966775386/CleanShot_2025-04-03_at_18.33.192x.png?ex=67f08875&is=67ef36f5&hm=b55e2006ae8c7f6f4cc21763315ff16163bca38b73b5d227eb435abb3ee3222a&