How Warm Transfers Work

When servicing a call, a call center agent often performs one of two possible transfers:

1. ❄️ A cold transfer

2. 🔥 A warm transfer

What is the difference between these two you ask? Let us discuss.

Cold Transfers

A cold transfer, also known as a blind transfer, occurs when a call is transferred to another person (agent) without any introduction or background information provided to the recipient. The agent receiving the call has no context about the caller's needs, which can lead to a lower quality customer experience.

Cold transfers are typically used when the caller needs to be directed to a specific person or department without the need for additional context, like when the caller called the wrong department or is looking for a particular recipient.

Warm Transfers

A warm transfer on the other hand is when the agent puts the caller on hold, calls the escalation agent and provides a background, and then merges the two calls. Warm transfers typically enhance customer service by making sure the caller doesn't have to repeat their information.

For example, if a customer needs to speak to a specialist, the initial representative will explain the situation to the specialist before transferring the call.

Here’s the process for a warm transfer:

Figure 1 Process flow for a warm transfer

Warm Transfer: Technical Architecture

The diagram above is helpful to understanding the process as it pertains to the customer experience, however, behind the scenes, there’s a fair bit more going on. Step 3 of the transfer process, where the customer is transferred to a conference call (and put on hold) and the virtual agent makes a second phone call to a human agent.

Figure 3 Agent summarizes your customer’s needs to the escalation agent (human agent)

The warm_transfer algorithm looks like this:

1. Transfer the current call to a Twilio conference, and extract the conference Id.

2. Create a summary of the current call

3. Create a new outbound call request to call the escalation agent. Use the streamUrl in your TwimL instructions to encode these two data elements (conference_id and call_summary).

4. Disconnect.

5. The second stream that is connected between escalation agent (human) and a “call transfer” agent who’s instructions are to summarize the previous call, and has only one function complete_transfer.

6. The call transfer agent summarizes the call to their human colleague, and then joins the human agent to the conference described by conference_id.

And that’s it, that’s how a warm transfer is facilitated on a live telephone call between three call attendees!