I am using Vapi's outbound calling API for outbound calls. Now, I am implementing my custom call transfer function because I needed some customization in call transfers that wasn't possible with Vapi's built-in call transfer. I have defined the call transfer criteria in the prompt and have set up a function tool in the assistant, where I provided the server URL for my custom transfer function. When the assistant attempts to perform the call transfer, it sends a request to this server URL, and the custom call transfer function I implemented runs. However, the issue I'm facing is that when the custom transfer call function is triggered, the Vapi outbound call disconnects. Can someone please explain why the phone call is disconnecting when calling the custom function through the server URL?