How to use Transfer Call

The Transfer Call tool allows your AI agent to hand off an active call to a human agent, department, or any phone number — at exactly the right moment in a conversation. It supports both Cold Transfer (instant handoff) and Warm Transfer (assisted handoff with context sharing) to give you full control over how the transition happens.

Phone calls only. This tool works exclusively for phone calls and is not supported for web-based chat or voice sessions.

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When to Use

Trigger this tool when:

• The customer asks to speak with a human agent
• The request requires human judgement or specialist knowledge
• The conversation needs escalation (e.g., complaint, complex query)
• Routing to a specific department is required — Sales, Support, Billing, Renewals, Claims

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Steps to Add

1. Open the Agent Builder
2. Click + Add Tool
3. Select Voice Tool Call
4. From the Select Action dropdown, choose voice_transfer_call
5. Fill in all configuration fields (described below)
6. Click Add to Agent

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Step 1: Instruction (When this tool should be invoked)

Write a clear instruction that tells the AI agent when to trigger the transfer. The more specific you are, the more reliably the agent will initiate the transfer at the correct moment.

Transfer the call when the customer asks to speak with a human, expresses frustration,
or needs assistance that goes beyond what the AI can handle.

Transfer to the billing department when the customer raises a payment dispute
or questions their invoice amount.

Vague instructions like “transfer when needed” make it harder for the agent to decide. Always describe the exact trigger condition.

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Step 2: Transfer To

Defines where the call will be sent.

Destination Options

Option	Description
Static Destination	A fixed phone number or SIP URI — always routes to the same endpoint
Dynamic Routing	Destination is resolved at runtime from a {{variable_name}} extracted during the conversation

Accepted Formats

• Phone number (E.164 format): [phone]
• SIP URI: sip:[e-mail]
• Dynamic variable: {{assigned_agent_number}}

All phone numbers must be in E.164 international format, including the country code (e.g., +1 for US, +91 for India).

Extension Number (Optional)

After the main number connects, the extension routes the call to the correct internal team or agent — automatically, without the customer needing to press anything.

Main Number:  [phone]   ← connects to the company switchboard
Extension:    302               ← routes directly to the Billing team

Why the Extension Field Matters

Most business phone systems (PBX, RingCentral, 8x8, Vonage, Twilio) share a single main inbound number across departments. Without an extension, the AI agent connects to the front-line IVR or receptionist and stalls — requiring manual routing.

With the extension configured, the handoff is seamless: the agent dials the main number and immediately routes to the right desk, with no customer interaction needed.

When to Use the Extension

Your business has multiple departments on one main line:

Main: [phone]
├── ext. 101 → Sales
├── ext. 202 → Customer Support
└── ext. 303 → Billing & Accounts

You want to bypass the IVR entirely: Many phone systems allow direct extension dialing, skipping IVR menus altogether. The customer saves 30–60 seconds and reaches the right person immediately.

You’re routing to a specific named agent: If a customer has a dedicated account manager (e.g., ext. 415 for James in Renewals), the extension ensures they always land at the right person — not a random available agent.

You use SIP-based infrastructure: SIP URIs often require an extension to reach the correct endpoint. Without it, calls may fall back to a default destination.

Static vs. Dynamic Extension

Static — same extension on every transfer:

Extension: 302

Best for single-purpose bots where all transfers always go to one team.

Dynamic — extension resolved from conversation context:

Extension: {{department_extension}}

Pair this with Extract Dynamic Variables to map customer intent to the right extension at runtime:

Customer Says	Extracted Intent	Extension Routed
”I want to renew my policy”	renewals	201
”I need to file a claim”	claims	305
”I have a billing question”	billing	410
”I want to cancel”	cancellations	500

This lets a single Transfer Call tool handle all your departments — no need to create a separate tool for each one.

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Step 3: Transfer Type

SigmaMind provides two transfer types. Choose based on whether context sharing is needed before the customer connects.

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Cold Transfer

The AI agent immediately routes the call to the destination and disconnects.

What happens:

• The AI initiates the transfer and exits the conversation instantly
• The customer hears ringing and connects directly to the destination
• No context or summary is shared with the receiving agent

When to use Cold Transfer:

• Simple department routing where no background is needed
• Fast escalations where speed matters more than context
• Internal lines where agents already have CRM access

Customer: "Can I speak to someone in support?"
→ AI triggers voice_transfer_call
→ Call routes to [phone]
→ AI drops off immediately
→ Customer hears ringing, support agent picks up

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Warm Transfer

The receiving agent is connected first, context is shared privately, then the customer is bridged in. This creates a smooth, professional handoff experience.

Warm Transfer happens in two distinct stages:

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Stage 1: Connecting Stage

In the Connecting Stage, the receiving agent’s line is dialed and connected — but the customer and the agent cannot yet hear each other. The customer is still on hold, listening to ringing or hold music.

This stage exists so the receiving agent can receive context before the customer joins, allowing them to prepare a response or pull up the right information.

[Connecting Stage]
Customer ──── on hold (hears ringing) ────►
                                          AI ──► Agent connected
                                               ↓
                                          Whisper Message played to agent only

Whisper Message

The Whisper Message is a private audio message played only to the receiving agent during the Connecting Stage. The customer cannot hear it under any circumstances.

Use the Whisper Message to give the agent the context they need before they say hello — customer name, reason for calling, policy number, account history, or any other relevant detail.

To enable Whisper Message:

1. Toggle Whisper Message ON
2. Enter your message in the text box
3. Choose either Static or Prompt mode

Static Whisper Message

A fixed, pre-written message — the same text plays on every transfer.

You are being connected to a customer regarding an insurance renewal request.
Please review their policy and assist accordingly.

You can make static messages smarter by embedding dynamic variables:

You are being connected to {{customer_name}} regarding insurance policy {{policy_id}}.
The customer wants assistance with {{request_type}}.
Please have their account ready before greeting them.

Best for: predictable, structured use cases where the context format never changes.

Prompt Whisper Message

Instead of writing a fixed message, you provide an instruction — and SigmaMind AI automatically generates a contextual summary based on the actual conversation before playing it to the agent.

Prompt instruction:

Summarize the customer's request and include their name, issue, and requested service.

What the system generates automatically (example output):

Customer name is Rahul Sharma. He is calling to renew his car insurance policy
and wants clarification on premium pricing and coverage details.

Prompt with variables:

Provide a short summary for the receiving agent. Include customer name {{customer_name}},
service {{service_type}}, and request {{customer_request}}.

Best for: conversations where the context varies widely — complaints, complex queries, multi-topic calls — and a fixed script wouldn’t cover every scenario.

If the Whisper Message is left empty, the transfer will still proceed, but no context will be shared with the receiving agent. In this case, the Warm Transfer effectively behaves like a Cold Transfer.

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Stage 2: Bridged Stage

In the Bridged Stage, the call bridge is established and both the customer and the receiving agent can now hear each other. The AI agent drops off, and the human takes over the conversation.

This is the moment the transfer is truly complete.

[Bridged Stage]
Customer ◄──────────────────────────► Human Agent
               (full duplex audio)
AI drops off

Three-Way Message (Bridge Message)

At the moment of bridging, the AI can play one final message heard by both the customer and the receiving agent simultaneously. This ensures a clear, professional transition and eliminates any awkward silence or confusion about whether the connection has succeeded.

To enable Three-Way Message:

1. Toggle Three-way Message ON
2. Enter the message in the text box
3. Choose either Static or Prompt mode

Static Three-Way Message

A fixed announcement confirming the connection:

Thank you for waiting. You are now connected to our support specialist.

With dynamic variables:

Thank you for waiting, {{customer_name}}. You are now connected to our support specialist.

Prompt Three-Way Message

A dynamically generated message tailored to the specific call:

Generate a short, clear, and neutral three-way message to be played to both the customer
and the agent after the call is bridged. Confirm the connection is complete and invite
the conversation to continue. Keep it professional and concise.

With variables:

Generate a short, clear, and neutral three-way message to be played to both {{customer_name}}
and the agent after the call is bridged. Mention that {{customer_name}} is now connected
with the {{agent_role}} regarding {{call_reason}}.
Keep it professional, concise, and welcoming.

All variables must always be written using double curly braces: {{variable_name}}

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Step 4: Custom Headers (Optional)

Custom Headers let you send structured metadata along with the call transfer. This information is invisible to the customer but available to the receiving agent’s system, CRM, call center software, or backend automation.

Headers are sent as key-value pairs:

X-Intent: billing_issue
X-Language: en
X-Customer-Type: existing
X-Ticket-ID: 12345
X-Call-Source: outbound_campaign
X-Policy-ID: POL-98271

When Custom Headers Are Useful

Use Case	Header Example
Route to the right CRM queue	X-Intent: claims_inquiry
Tag language for multilingual teams	X-Language: hi
Associate call with a campaign	X-Call-Source: renewal_campaign_Q2
Pre-load customer record	X-Customer-ID: CUS-00421
Log call reason for reporting	X-Call-Reason: cancellation_request

Headers provide structured context for automation, reporting, and agent preparation — all without requiring the customer to repeat themselves.

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Step 5: Add to Agent

Once all fields are configured, click Add to Agent to save the tool.

If the receiving agent does not answer or the transfer fails due to network issues, SigmaMind automatically retries the transfer based on your configured settings.

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Full Warm Transfer Execution Flow

Customer requests transfer
        ↓
AI triggers voice_transfer_call
        ↓
[Connecting Stage]
Receiving agent's line is dialed
Customer placed on hold (hears ringing)
        ↓
Whisper Message played to agent only
(Customer cannot hear this)
        ↓
[Bridged Stage]
Call bridge established
Both customer and agent can hear each other
        ↓
Three-way Message played to both parties
        ↓
AI drops off
Human agent continues the conversation

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Cold vs. Warm

Feature	Cold Transfer	Warm Transfer
Agent connected before customer	❌	✅
Whisper Message to receiving agent	❌	✅
Three-way bridge announcement	❌	✅
Customer hears hold music	❌	✅
Context shared before handoff	❌	✅
Speed	Fastest	Slightly slower (seconds)
Best for	Simple routing	High-stakes or complex calls

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Example Configurations

Example 1 — Cold Transfer to Support

Field	Value
Instruction	Transfer when the customer requests a human agent.
Transfer To	Static → [phone]
Extension	202
Transfer Type	Cold Transfer

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Example 2 — Warm Transfer with Whisper + Bridge Message

Field	Value
Instruction	Transfer when the customer raises a billing dispute or payment issue.
Transfer To	Static → [phone]
Extension	{{department_extension}}
Transfer Type	Warm Transfer
Whisper Message	You are being connected to {{customer_name}} regarding a billing dispute on policy {{policy_id}}.
Three-way Message	Thank you for waiting, {{customer_name}}. You are now connected with our billing specialist.

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Best Practices

• Write specific trigger instructions — vague conditions cause missed or premature transfers
• Use Warm Transfer for high-value calls, complaints, or any scenario where the receiving agent benefits from knowing context upfront
• Use Prompt Whisper Messages when call topics vary widely — the AI generates a tailored summary every time
• Pair Dynamic Routing with Extract Dynamic Variables to handle multi-department routing from a single transfer tool
• Use Custom Headers to pre-load CRM records or tag calls for analytics — reduces repeat questions for the customer
• Always enter phone numbers in E.164 format (+[country code][number])
• Test transfer flows using the Test Voice playground before going live

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Troubleshooting

Issue	Fix
Transfer not triggering	Make the Instruction more specific and match actual conversation phrases
Call drops instead of transferring	Verify phone number is in correct E.164 format
Extension not connecting	Confirm the extension is active on your PBX/phone system and accepts auto-dial
Dynamic variable not resolving	Ensure Extract Dynamic Variables runs earlier in the agent flow
Whisper message not playing	Check that the Whisper Message toggle is ON and the message text is not empty
Warm transfer behaves like cold	Whisper Message is likely empty — add content to distinguish the stages
Three-way message not heard	Confirm the Three-way Message toggle is ON in the Bridged Stage settings