When calls show SIP completed, 0 logs, it usually means the session never fully initializes after config return. Here are the things you should check, Make sure the assistantId is explicitly included in the returned config (not just implied). Confirm the response is 200 OK and under timeout (no 3–5s delay). Validate the JSON exactly matches Vapi schema (even one misplaced field can silently fail). Make sure you’re not mixing orgs or environments. The “set assistant ID” message usually means Vapi didn’t attach it post-parse not that your endpoint wasn’t hit. Send me the config you’re returning (sanitized) and I’ll spot the issue fast. And yeah… the dropdown situation is… ambitious.