Cold Transfer
Immediately connects the caller to the destination number without any briefing. How it works:- AI informs caller they’re being transferred
- Call connects directly to destination
- AI disconnects immediately
Technical detail: Cold transfers use the SIP REFER method. For every cold
transfer, telli includes
X-Telli-Call-Id in the SIP REFER request headers,
with the telli call id as its value for downstream call correlation.Warm Transfer
Places caller on hold while the AI briefs the human agent before connecting them. How it works:- AI places caller on hold with music
- AI calls destination in a separate session
- AI summarizes the conversation for the human agent
- Human agent accepts or declines the transfer
- If accepted: caller connects to the briefed agent
- If declined/unavailable: AI returns to caller with explanation
- Human receives conversation summary before speaking to customer
- Automatic detection of voicemail or unavailability
- AI can resume conversation if transfer fails
- Better customer experience with informed handoff
Timeout Handling
| Scenario | Detection Time | Result |
|---|---|---|
| No answer | 5 minutes max | AI returns to caller |
| Voicemail detected | 10-30 seconds | AI returns immediately |
| Agent says unavailable | Immediate | AI returns immediately |
| Caller hangs up | Immediate | Transfer cancelled |
Configuration
1. Add Transfer Numbers
Navigate to Agent Settings → Calls → Transfer Configurations Required fields:- Label: Internal name (e.g., “Sales Team”)
- Phone Number: E.164 format (e.g., +4917612345678)
- Description: When to use this transfer (e.g., “For customers ready to purchase”)
- Transfer Type: Choose Cold or Warm
You can add multiple transfer destinations. The AI will choose based on
conversation context.