SIP Trunk Setup for AI Agent

I need clear, step-by-step guidance to connect my current VoIP provider’s SIP trunk to Retell so that incoming calls are automatically handed over to an AI answering agent whenever all human operators are busy. The goal is not only to keep the phone lines open but also to make sure the transition between live staff and the AI is seamless for the caller.

Here is what I expect from you:
Through a screen share session walk me though the Setting to make retell ai receive inbound call to my number. Reteall AI will then fire an AI agent to life.

I already have administrator access to both the VoIP portal and the Retell dashboard, so you can reference specific menus or API fields. Assume I’m technically comfortable but new to this specific integration.

Once I can place a live call, watch it overflow to the AI, and see the dialogue complete without errors, I’ll consider the job done. MUST be by live screen sharing.