RexaThe short answer
Warm transfer is the handoff that does not make the caller start over. The agent reaches the human first, passes context, and only then joins the caller in. For voice AI it is the crucial escalation path: the value of an agent that knows when to give up is largely destroyed if the handoff drops everything it learned.
In detail
Mechanically, the transferring party places the caller on hold, establishes a second leg to the target, holds a private consultation, then bridges the caller into that conversation or drops out of it. The caller experiences hold followed by a person who already knows why they are calling.
For a voice agent, the context passed at handoff is the entire point, and it can travel in two ways. A spoken whisper — the agent summarising the call to the human before the bridge — needs no integration and works with any receiving system. A screen pop, where the transcript and collected fields appear in the agent desktop as the call arrives, is faster for the human but requires the CRM integration to exist.
The cost is hold time and staffing. Warm transfer occupies both the caller and the receiving human during the consultation, and if the target does not answer the transferring party must recover gracefully rather than leaving the caller in silence. That recovery path — take a message, offer a callback, route elsewhere — is the part most implementations get wrong.
How Rexa handles it
Rexa agents transfer to a configured transfer_number in E.164 form, which requires transfer capability to be enabled on the agent. When a transfer begins the platform emits a session.transfer_initiated webhook carrying the session and the target number; the original call is still active at that point, so the event marks the start of the handoff rather than the end of the call.
Webhooks referenceRelated terms
Cold transfer
A cold transfer is a handoff in which the caller is sent to another destination immediately, with no consultation beforehand.
Call leg
A call leg is a single connection between the telephony platform and one endpoint, of which a complete call may contain several.
Voice agent
A voice agent is software that conducts a spoken conversation with a person over a phone line or a browser connection, understanding natural speech and responding in speech.
IVR
An IVR is an automated phone system that presents callers with a predefined menu and routes them according to keypad or spoken selections.