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PUT
Update Assistant
This endpoint allows you to update the configuration of an existing AI assistant. All fields are optional – only the fields provided will be updated. For detailed field descriptions and options, see Create Assistant.

Path Parameter

integer
required
The unique identifier of the assistant to be updated

Request Body

Core Fields

string
The name of the assistant (max. 255 characters)
integer
The voice ID to be used for the assistant. Use the Get Voices endpoint with the mode parameter to get voices compatible with your engine mode.
integer
The language ID for the assistant. Use the Get Languages endpoint to retrieve available languages.
string
The assistant type. Options: inbound, outbound
string
The engine mode. Options: pipeline, multimodal, dualplex
Changing the mode resets mode-specific settings to their default values for the new mode.
string
The timezone for the assistant (e.g., “Europe/Berlin”, “America/New_York”)
string
The initial message the assistant will speak at call start (max. 200 characters)
string
The system prompt defining the assistant’s behaviour and personality

Mode-Specific Fields

integer
The LLM model ID to use. Only applicable in pipeline mode.Use the Get Models endpoint to retrieve available models.
integer
The multimodal model ID. Applicable only in multimodal and dualplex modes.Use the Get Models endpoint to retrieve available multimodal models.
integer
Fallback LLM model ID for tool calls in multimodal/dualplex modes. Set to null to remove.
number
Sensitivity of speaker turn detection for multimodal/dualplex modes (0-1). Set to null for automatic.

Secondary Languages

integer[]
Array of additional language IDs the assistant can speak. Replaces existing secondary languages. Pass an empty array [] to remove all secondary languages.

Knowledgebase Settings

integer
The ID of the knowledgebase to link. Set to null to remove.
string
How to use the knowledgebase. Options:
  • function_call - AI calls a function to search (required for multimodal/dualplex)
  • prompt - Knowledge is injected into prompt (pipeline only)

Organization

integer
ID of a folder to move this assistant into. Must belong to your account. Set to null to make it uncategorized. Omit to leave the folder unchanged.
integer[]
Array of label IDs for this assistant. Each label must belong to your account. When provided, this replaces the assistant’s current labels. Omit to leave labels unchanged; send [] to remove all labels.

Phone Number

integer
The ID of a phone number to assign. Set to null to unassign. Must belong to your account.
For inbound assistants, the phone number cannot be a caller ID type and must not already be assigned to another inbound assistant.

Custom Mid-Call Tools

integer[]
Array of custom mid-call tool IDs to synchronize. Replaces all existing tool assignments. Pass an empty array [] to remove all tools. Each tool must belong to your account.

Built-in Tools

array
Array of built-in tools. Replaces all existing built-in tools. Pass an empty array [] to remove all tools.
When you list assistants, each configured tool is returned as { "type": "...", "data": { ... } } with the same field names nested under data (not top-level).

Speech and TTS Settings

boolean
Whether emotional text-to-speech synthesis is enabled
number
Voice stability setting (0-1). Higher = more consistent voice
number
Voice similarity setting (0-1). Higher = closer to original voice
number
Speech speed multiplier (0.7-1.2)
number
LLM temperature setting (0-1). Lower = more deterministic
integer
Custom TTS provider ID. Set to null to use the system default voice. See Get Synthesizer Providers.
integer
Custom STT provider ID. Pipeline mode only. Set to null to use the system default voice. See Get Transcriber Providers.

Call Behavior Settings

boolean
Whether caller interruptions are allowed.
Cannot be disabled in multimodal and dualplex modes.
boolean
Whether filler audio should be used during processing.
Available only in pipeline mode.
object
Custom filler profiles per category. Replaces the existing filler configuration. Each category is an array of short phrases.
  • positive: Fillers for affirmative responses
  • negative: Fillers for negative/neutral responses
  • question: Fillers when processing a question
  • neutral: Fillers for neutral confirmations
boolean
Whether the call should be recorded
boolean
Whether noise cancellation should be enabled
boolean
If true, the assistant waits for the customer to speak first

Timing Settings

integer
Maximum call duration in seconds (20-1200)
integer
Maximum silence duration before re-engagement in seconds (1-360)
integer
Maximum silence at the start of the call before termination (1-120 seconds). Set to null to disable.
integer
Maximum ringing time before aborting (1-60 seconds)

Re-Engagement Settings

integer
Interval for re-engagement in seconds (7-600)
string
Custom prompt for re-engagement messages (max. 1000 characters). Set to null to use the default.

Voicemail Settings

boolean
Whether to end the call when voicemail is detected
string
Message to leave on voicemail before hanging up (max. 1000 characters). Set to null to disable.

Endpoint Detection

string
Type of voice activity detection. Options: vad, ai
number
Endpoint sensitivity level (0-5)
number
Interruption sensitivity level (0-5)
integer
Minimum number of words before interruption is allowed (0-10). Set to null to disable.

Ambient Sound

string
Background ambient sound. Options: off, office, city, forest, crowded_room, cafe, nature
number
Volume of the ambient sound (0-1)

Webhook Configuration

boolean
Whether webhook notifications are enabled
string
The webhook URL for post-call notifications. Set to null to remove.
boolean
Whether webhooks should be sent only for successfully completed calls (not on failed/no-answer)
boolean
Whether the recording URL should be included in the webhook payload

Post-Call Evaluation

boolean
Whether AI-based post-call evaluation is enabled
array
Schema definition for extracting post-call data. Replaces the existing schema.

Variables

object
Key-value pairs for custom variables. Replaces all existing variables.

Example Requests

Update Basic Settings

Switch to Multimodal Mode

Update Tools and Knowledgebase

Update Re-Engagement and Voicemail

Remove Optional Settings


Response

string
Success message confirming the assistant update
object

Notes

  • Only the fields you provide in the request body will be updated
  • To remove optional fields, explicitly set them to null
  • To clear arrays (tools, secondary languages), pass an empty array []
  • The assistant must belong to the authenticated user
  • Use the Get Voices endpoint with the mode parameter to get compatible voices
  • For multimodal/dualplex modes, knowledgebase_mode must be set to function_call
  • In multimodal/dualplex modes, interruptions (allow_interruptions) cannot be disabled
  • Changing mode resets mode-specific settings (LLM model, multimodal model, providers)