Agentic Warm Transfer for voice agents

Voice agents have a new transfer type, Agentic Warm Transfer. Before the caller is connected, a transfer agent talks with the destination and decides whether to bridge the call or cancel it and return the caller to the main agent. Create the transfer agent from the Transfer Call action, and its prompt and actions are set up for you. At launch it isn't available in every workspace or for agents that use a SIP trunk caller ID.