Amazon Connect - Flow for Voicemail

You don't have to transfer the call out, leave it in that flow and just do you VM logic in there. Be aware that if the agent becomes available they will be pulled out of that logic and sent to an agent.

I would instead offer them a callback... Voicemails tend to be mostly... "Heres my phone number, please call me back". Then you need to allocate an agent to be unavailable on phones, and off listening to recorded messages...

Transferring to a callback instead means the call gets offered to an agent as it reaches the front of the queue, and the customer will receive a call, and you don't have to allocate anyone to the task of listening to recorded messages.