Autonomous Silence Handling

Technical documentation for the autonomous_silence_handling feature.

Overview

Autonomous Silence Handling is a feature that allows the AI assistant to intelligently detect and respond to prolonged silence during a call. When enabled, the assistant will:

Detect when the caller has stopped speaking

Prompt the caller to check if they're still on the line

After multiple attempts without response, gracefully end the call

This prevents calls from hanging indefinitely when callers walk away, get disconnected, or put the phone down.

Configuration

Assistant Schema

{
  "autonomous_silence_handling": true
}

Field	Type	Default	Description
`autonomous_silence_handling`	boolean	`false`	Enable/disable autonomous silence detection

Automatic Tool Addition

When autonomous_silence_handling is enabled, the system automatically adds the end_call tool to the assistant's toolset if not already present. This ensures the assistant can hang up after detecting prolonged silence.

How It Works

Timing Configuration

Parameter	Value	Description
`first_silence_check`	7 seconds	Time before first prompt after silence detected
`silence_check_interval`	12 seconds	Time between subsequent prompts
`max_silence_attempts`	3	Maximum prompts before instructing assistant to hang up

State Machine

[User Speaking] → [User Away] → [Silence Check 1] → [Silence Check 2] → [Silence Check 3] → [Hang Up]
       ↑              │                │                   │                   │
       └──────────────┴────────────────┴───────────────────┴───────────────────┘
                              (User speaks → reset timer)

Event Flow

User State: "away" - Silence timer starts

7 seconds pass - First silence check triggered

Assistant speaks - "Are you still there?" (contextual)

12 more seconds - Second silence check

Assistant speaks - "I'm still here if you need me"

12 more seconds - Third and final check

Assistant speaks - Brief goodbye + calls end_call tool

Contextual Prompts

The assistant receives different instructions based on the attempt number:

Attempt 1:

IMPORTANT: No speech detected from caller. This is attempt 1 of 3.
Based on context: if they said they need to look something up, say you'll wait.
Otherwise, ask a short question to check if they are still on the line.

Attempt 2:

IMPORTANT: Still no speech from caller. This is attempt 2 of 3.
Ask one more time if they are still there.
If no response after this, you will need to end the call.

Attempt 3 (Final):

IMPORTANT: No speech detected from caller for a long time.
This is attempt 3 of 3.
You must now say a brief goodbye and immediately use end_call to hang up.

Key Behaviors

No check while assistant speaking: Silence timer pauses when assistant is speaking

Reset on user speech: Any detected user speech resets the timer and attempt counter

Graceful termination: Assistant is instructed to say goodbye before hanging up

Context-aware: First prompt considers conversation context (e.g., "let me look that up")

Use Cases

Good For

Reception/Front Desk: Callers may walk away to check something

Customer Support: Long hold times while customers search for info

Appointment Booking: Callers checking their calendars

Consider Disabling For

Emergency Lines: May need to stay connected even during silence

Listening Services: Where silence is expected and acceptable

IVR/Menu Systems: Where users navigate with keypresses, not speech

Interaction with Other Features

With `voicemail_detection`

Both can be enabled simultaneously. Voicemail detection triggers first (on initial greeting), while silence handling activates during the conversation.

With `max_duration_seconds`

If max_duration_seconds is set, the call will end at that time regardless of silence handling state.

With `end_call` Tool

If the assistant already has end_call in its tools, no duplicate is added. The silence handling instructions simply tell the assistant to use the existing tool.

Webhook Events

When a call ends due to silence handling:

{
  "message": {
    "type": "end-of-call-report",
    "call": {
      "status": "ended"
    },
    "summary": "Call ended after no response from caller..."
  }
}

The status-update webhook will show status: "ended" (not a special silence-related status).

Troubleshooting

Assistant Not Detecting Silence

Verify autonomous_silence_handling: true is in the assistant configuration

Check the call transcript to see if silence detection prompts appear

Ensure STT (Speech-to-Text) is properly configured to detect when user stops speaking

Assistant Ending Calls Too Quickly

The 7-second initial delay should prevent premature endings

Review the call transcript to see timing of silence prompts

Note that timing parameters (7s, 12s, 3 attempts) are currently fixed

Assistant Not Hanging Up After 3 Attempts

The end_call tool is automatically added when silence handling is enabled

Review the end-of-call-report to see if the assistant attempted to end the call

The LLM may occasionally not follow instructions perfectly - this is expected behavior with AI assistants

Autonomous Silence Handling

Overview#

Configuration#

Assistant Schema#

Automatic Tool Addition#

How It Works#

Timing Configuration#

State Machine#

Event Flow#

Contextual Prompts#

Key Behaviors#

Use Cases#

Good For#

Consider Disabling For#

Interaction with Other Features#

With voicemail_detection#

With max_duration_seconds#

With end_call Tool#

Webhook Events#

Troubleshooting#

Assistant Not Detecting Silence#

Assistant Ending Calls Too Quickly#

Assistant Not Hanging Up After 3 Attempts#