Warm vs Cold Transfer: Choosing the Right Mode
When your AI agent transfers a call to a human, there are two ways it can happen: warm transfer and cold transfer. Each transfer number can have its own mode, so you can mix and match based on the situation.
What's the Difference?
Warm Transfer | Cold Transfer | |
How it works | AI calls you first, briefs you about the caller, then connects them after you accept | Caller is immediately forwarded to your phone — no briefing, no approval step |
Speed | Takes longer (15–30 seconds for the briefing + accept flow) | Instant — caller hears ringing within seconds |
Context | You know who's calling and why before you pick up | You pick up blind — no context about the caller |
Caller experience | Hears hold music while AI briefs you | Hears standard ringing, feels like a normal call forward |
You can decline? | Yes — AI continues the conversation if you decline | No — call goes through immediately, like regular forwarding |
Warm Transfer (Default)
This is the default mode and works best for most businesses. Here's what happens step by step:
AI tells the caller: "One moment, I'm connecting you now"
Caller hears hold music
AI calls your transfer number in a separate conversation
AI briefs you: who's calling, what they need, and a quick summary of the conversation so far
You accept or decline the transfer
If accepted, the caller is connected to you directly and AI steps out
Best for: High-value calls, sales inquiries, complex support issues — situations where knowing context before picking up helps you serve the caller better.
Cold Transfer
Cold transfer skips the briefing entirely. The caller is forwarded directly to your phone via SIP, just like traditional call forwarding:
AI tells the caller: "One moment, I'm connecting you now"
Caller is immediately forwarded — they hear ringing
You pick up as you would any normal call
Best for: Simple call routing, receptionists, situations where speed matters more than context, or when you already know who's likely calling (e.g., a dedicated support line).
What If You Don't Pick Up or It Hits Voicemail?
This is an important difference between the two modes:
Warm transfer: The AI calls your number to brief you. If you don't answer or the call hits voicemail, the AI cannot complete the handoff. The transfer fails and the AI returns to the caller with an error — the caller gets a poor experience.
Cold transfer: The caller is forwarded directly to your phone. If you don't pick up, the caller reaches your voicemail and can leave a message — just like a normal call. No dead end.
Recommendation: If there's a chance you won't always be available to answer, use cold transfer. That way the caller can at least leave a voicemail instead of getting bounced back to the AI with an error.
How to Set the Transfer Mode
Go to Agents → select your agent → Transfer tab
Add a new transfer number or edit an existing one
Under Transfer mode, choose Warm or Cold
Save
Each transfer number has its own mode. For example, you might use warm transfer for your sales line (so you know the lead's interest before answering) and cold transfer for your front desk (where quick pickup matters most).
What Happens If Warm Transfer Fails?
If the warm transfer cannot be completed (e.g., the briefing call fails for technical reasons), the system automatically falls back to a cold transfer. The caller will still be connected — they just won't get the briefing step.
Frequently Asked Questions
Can I use different modes for different numbers?
Yes. Each transfer number has its own transfer mode. You can set sales to warm and support to cold, or any combination you need.
Which mode should I use if I'm not sure?
Start with warm transfer (the default). It gives you more control and context. Switch to cold if you find the briefing step adds unnecessary delay for a specific number.
Does the transfer mode affect billing?
Warm transfers use slightly more minutes because the AI makes a separate call to brief you. Cold transfers are quicker and use less time.
Will the caller notice the difference?
Yes. With warm transfer, they hear hold music for 15–30 seconds. With cold transfer, they hear ringing almost immediately. Both start with AI announcing the transfer.