Send Call

Headers

authorization

string

required

Your API key for authentication.

encrypted_key

string

A special key for using a BYOT (Bring Your Own Twilio) account. Only required for sending calls from your own Twilio account.

Body

phone_number

string

required

The phone number to call. Country code defaults to +1 (US) if not specified.For best results, use the E.164 format.

Formatting Examples

Expected/Ideal Format

“+12223334444”
“+91223334444”
“+61223334444”

Valid, but not recommended:

“2223334444”
“+1 (222) 333-4444”
“+1 222 333 4444”
“222-333-4444”

Invalid

“12223334444”
“552223334444”
“non-numeric characters”
“2223334444 ext. 123”

task

string

required

Provide instructions, relevant information, and examples of the ideal conversation flow.This is your prompt where you are telling the agent what to do.Recommendations:

Include context and a background/persona for the agent like "You are {name}, a customer service agent at {company} calling {name} about {reason}.
Phrase instructions like you are speaking to the agent before the call.
Any time you tell the agent not to do something, provide an example of what they should do instead.
Keep the prompt under 2,000 characters where possible.
Want to easily test out exactly how your agent will behave? Try out Agent Testing!

pathway_id

string

This is the pathway ID for the pathway you have created on our dev portal. You can access the ID of your pathways by clicking the ‘Copy ID’ button of your pathway hereNote: Certain parameters do not apply when using pathways.

Unused Parameters

task - The pathway substitutes as the agent’s instructions.
model - We use our own fine-tuned models under the hood.
tools - Replaced by ‘Webhook’ Node in Pathways
transfer_list - Replaced by ‘Transfer Call’ Node in Pathways
transfer_phone_number - Replaced by ‘Transfer Call’ Node in Pathways

Example Simple Request body:

{
    "phone_number": "+1975934749",
    "pathway_id": "a0f0d4ed-f5f5-4f16-b3f9-22166594d7a7"
}

start_node_id

string

This is the node ID for the node you want the pathway to start from. You can access the ID of your nodes hereNote: This parameter is only used when pathway_id is provided.Example Simple Request body:

{
    "phone_number": "+1975934749",
    "pathway_id": "a0f0d4ed-f5f5-4f16-b3f9-22166594d7a7",
    "start_node_id": "a0cd5fed-f3f3-5412-1339-13567921d7b8"
}

Agent Parameters (Body)

voice

string

default:"mason"

The voice of the AI agent to use. Accepts any form of voice ID, including custom voice clones and voice presets.Default voices can be referenced directly by their name instead of an id.Usage example: voice: "maya"voiceaura Curated voices:

maya
mason
ryan
adriana
tina
matt
evelyn

Use the GET /v1/voices endpoint to see a full list of your available voices.

Moving from `voice_id` to `voice`

Note: Including voice_id or reduce_latency in your request is still supported, but not recommended.The previous structure to select voices used both voice_id and reduce_latency. To simplify the process, we’ve combined these into a single voice parameter.

If the first two letters of voice are RL, that is equivalent to settings reduce_latency to true.
Prefixing the voice ID with HQ will use the high fidelity version of the voice.
The integer following the prefix is the voice_id from before.

Example:

reduce_latency: true, voice_id: 0 is equivalent to voice: "RL0"
reduce_latency: false, voice_id: 3 is equivalent to voice: "HQ3"

Including reduce_latency may override the voice parameter, so exclude it when using voice.

Moving from `voice_preset_id` to `voice`

All presets have been migrated to the voice parameter and can use either the preset name or ID.If you used to have a voice_preset_id of "2f9fdbc7-4bf2-4792-8a18-21ce3c93978f", you can now use voice: "2f9fdbc7-4bf2-4792-8a18-21ce3c93978f".

background_track

string

Select an audio track that you’d like to play in the background during the call. The audio will play continuously when the agent isn’t speaking, and is incorporated into it’s speech as well.Use this to provide a more natural, seamless, engaging experience for the conversation. We’ve found this creates a significantly smoother call experience by minimizing the stark differences between total silence and the agent’s speech.Options:

null - Default, will play audible but quiet phone static.
office - Office-style soundscape. Includes faint typing, chatter, clicks, and other office sounds.
cafe - Cafe-like soundscape. Includes faint talking, clinking, and other cafe sounds.
restaurant - Similar to cafe, but more subtle.
none - Minimizes background noise

first_sentence

string

Makes your agent say a specific phrase or sentence for it’s first response.

wait_for_greeting

boolean

default:"false"

By default, the agent starts talking as soon as the call connects.When wait_for_greeting is set to true, the agent will wait for the call recipient to speak first before responding.

block_interruptions

boolean

default:"false"

When set to true, the AI will not respond or process interruptions from the user.

interruption_threshold

number

default:"100"

Adjusts how patient the AI is when waiting for the user to finish speaking.Lower values mean the AI will respond more quickly, while higher values mean the AI will wait longer before responding.Recommended range: 50-200

50: Extremely quick, back and forth conversation
100: Balanced to respond at a natural pace
200: Very patient, allows for long pauses and interruptions. Ideal for collecting detailed information.

Try to start with 100 and make small adjustments in increments of ~10 as needed for your use case.

temperature

float

default:"0.7"

A value between 0 and 1 that controls the randomness of the LLM. 0 will cause more deterministic outputs while 1 will cause more random.Example Values: "0.9", "0.3", "0.5"

keywords

string[]

default:"[]"

These words will be boosted in the transcription engine - recommended for proper nouns or words that are frequently mis-transcribed.For example, if the word “Reece” is frequently transcribed as a homonym like “Reese” you could do this:

    {
        "keywords": ["Reece"]
    }

For stronger keyword boosts, you can place a colon then a boost factor after the word. The default boost factor is 2.

    {
        "keywords": ["Reece:3"]
    }

pronunciation_guide

array

The pronunciation guide is an array of objects that guides the agent on how to say specific words. This is great for situations with complicated terms or names.

    [
        {
            "word": "example",
            "pronunciation": "ex-am-ple",
            "case_sensitive": "false",
            "spaced": "false"
        },
        {
            "word": "API",
            "pronunciation": "A P I",
            "case_sensitive": "true",
            "spaced": "true"
        }
    ]

Object Parameters

word — the word you want to guide the LLM on how to pronounce
pronunciation — the word you want to guide the LLM on how to pronounce.
case_sensitive — whether or not to consider case. Particularly useful with names. EG: ‘Max’ the name versus ‘max’ the word. Defaults to false. Not required.
spaced — whether or not to consider spaces. When true the word ‘high’ would be flagged but NOT ‘hightop’. Defaults to true. Not required.

transfer_phone_number

string

A phone number that the agent can transfer to under specific conditions - such as being asked to speak to a human or supervisor.

Prompting Notes

For best results:

Specify conditions that the agent should transfer to a human under (examples are great!)
In the task, refer to the action solely as “transfer” or “transferring”.
Alternate phrasing such as “swap” or “switch” can mislead the agent, causing the action to be ignored.

transfer_list

object

Give your agent the ability to transfer calls to a set of phone numbers.Overrides transfer_phone_number if a transfer_list.default is specified.Will default to transfer_list.default, or the chosen phone number.Example usage to route calls to different departments:

{
    "transfer_list": {
        "default": "+12223334444",
        "sales": "+12223334444",
        "support": "+12223334444",
        "billing": "+12223334444"
    }
}

language

string

default:"en-US"

Select a supported language of your choice. Optimizes every part of our API for that language - transcription, speech, and other inner workings.

Expand to view language options

The available language options are as follows:

en - English
en-US - English (US)
en-GB - English (UK)
zh - Chinese (Mandarin, Simplified)
zh-CN - Chinese (Mandarin, Simplified, China)
zh - Hans - Chinese (Mandarin, Simplified, Hans)
zh - TW -Chinese (Mandarin, Traditional)
zh - Hant - Chinese (Mandarin,Traditional, Hant)
es - Spanish
fr - French
de - German
hi - Hindi
ja - Japanese
ko - Korean
pt - Portuguese
it - Italian
nl - Dutch
pl - Polish
ru - Russian
sv - Swedish
da - Danish
id - Indonesian
ms - Malay
tr - Turkish

timezone

string

default:"America/Los_Angeles"

Set the timezone for the call. Handled automatically for calls in the US.This helps significantly with use cases that rely on appointment setting, scheduling, or behaving differently based on the time of day.Timezone options are here in the TZ identifier column.

request_data

object

Any JSON you put in here will be visible to the AI agent during the call - and can also be referenced with Prompt Variables.For example, let’s say in your app you want to programmatically set the name of the person you’re calling. You could set request_data to:

      {
        "phone_number": "+1...",
        "task": "...",
        "first_sentence": "Hello {{name}}! How are you doing today?", // also works in the prompt, tools, etc.
        "request_data": {
        "name": "John Doe",
        }
    }

For further information about how Prompt Variables work, check out the Custom Tools tutorial.

tools

array

Interact with the real world through API calls.Detailed tutorial here: Custom Tools

dynamic_data

array

Make dynamic requests to external APIs and use the data in your AI’s responses.

Properties

Each request object should contain:url: The URL of the external API to fetch data from.response_data: An array of objects describing how to parse and use the data fetched from the API. Explained in more detail below.The following are optional:method: Allows GET or POST. Default: GETcache: Whether to fetch the data once at the beginning of the call, or to re-check continuously for data that might change mid-call. Default: trueheaders: An object of headers to send with the request.body: The body of the request.The following variables can be injected into the dynamic request body:

{{from}} (Ex. +12223334444)
{{to}}
{{short_from}} (Ex. 2223334444)
{{short_to}}
{{call_id}}

These string values will be replaced in each dynamic_data[].body where they’re used by system values in each request.Try out with this example:

{
    "dynamic_data": [
        {
            "url": "https://api.coindesk.com/v1/bpi/currentprice.json",
            "response_data": [
                {
                    "name": "BTC Price USD",
                    "data": "bpi.USD.rate",
                    "context": "Current BTC Price: ${{BTC Price USD}} USD"
                },
                {
                    "name": "BTC Price EUR",
                    "data": "bpi.EUR.rate",
                    "context": "In Euros: {{BTC Price USD}} EUR"
                }
            ]
        }
    ]
}

dynamic_data[i].response_data

array

An array of objects describing how to parse and use the data fetched from the API.Each object in this array should contain:

name: A label for the fetched data.
Example: "Flight Status"
data: The JSON path in the API response to extract the data from.
Example: "user.flights[0].status"
context: How this data should be incorporated into the AI’s knowledge.
Example: "John's flight is currently {{Flight Status}}"

Call Parameters (Body)

start_time

string

The time you want the call to start. If you don’t specify a time (or the time is in the past), the call will send immediately.Set your time in the format YYYY-MM-DD HH:MM:SS -HH:MM (ex. 2021-01-01 12:00:00 -05:00).The timezone is optional, and defaults to UTC if not specified.Note: Scheduled calls can be cancelled with the POST /v1/calls/:cal\l_id/stop endpoint.

voicemail_message

string

When the AI encounters a voicemail, it will leave this message after the beep and then immediately end the call.Warning: If amd is set to true or voicemail_action is set to ignore, then this will still work for voicemails, but it will not hang up for IVR systems.

voicemail_action

enum

default:"hangup"

This is processed separately from the AI’s decision making, and overrides it.Options:

hangup
leave_message
ignore

Examples:

Call is answered by a voicemail (specifically with a beep or tone):
- If voicemail_message is set, that message will be left and then the call will end.
- Otherwise, the call immediately ends (regardless of amd)
Call is answered by an IVR system or phone tree:
- If amd is set to true, the AI will navigate the system and continue as normal.
- If voicemail_action is set to ignore, the AI will ignore the IVR and continue as normal.
- Otherwise, if voicemail_message is set then it’ll leave that message and end the call.
- Finally, if none of those conditions are met, the call will end immediately.

Note: If voicemail_message is set, then the AI will leave the message regardless of the voicemail_action.

retry

object

If the call goes to voicemail, you can set up the call to retry, after a configurable delay. You can also update the voicemail_action, and voicemail_message in the retry object, for the re-tried call.Takes in the following parameters:

wait (integer): The delay in seconds before the call is retried.
voicemail_action (enum): The action to take when the call goes to voicemail. Options: hangup, leave_message, ignore.
voicemail_message (string): The message to leave when the call goes to voicemail.

Example:

    {
        "retry": {
            "wait": 10,
            "voicemail_action": "leave_message",
            "voicemail_message": "Hello, this is a test message."
        }
    }

max_duration

integer

default:"30"

When the call starts, a timer is set for the max_duration minutes. At the end of that timer, if the call is still active it will be automatically ended.Example Values: 20, 2

record

boolean

default:"false"

To record your phone call, set record to true. When your call completes, you can access through the recording_url field in the call details or your webhook.

from

string

Specify a phone number to call from that you own or have uploaded from your Twilio account. Country code is required, spaces or parentheses must be excluded.By default, calls are initiated from a separate pool of numbers owned by voiceaura.

webhook

string

When the call ends, we’ll send the call details in a POST request to the URL you specify here.The request body will match the response from the GET /v1/calls/:call_id endpoint.

webhook_events

string[]

Specify which events you want to stream to the webhook, during the call.Options:

queue
call
latency
webhook
tool
dynamic_data

Example Payload:

    {
        "message": "LLM: 411ms",
        "call_id": "0fb3c518-e941-48fd-a32c-67d59c541336",
        "category": "latency",
        "log_level": "performance"
    }

metadata

object

Add any additional information you want to associate with the call. This can be useful for tracking or categorizing calls.Anything that you put here will be returned in your webhook or in the call details under metadata.Example:

    {
        "metadata": {
            "campaign_id": "1234",
            "source": "web"
        }
    }

summary_prompt

string

At the end of each call, a summary is generated based on the transcript - you can use this field to add extra instructions and context for how it should be summarized.For example: "Summarize the call in French instead of English."

analysis_prompt

string

Guides the output and provides additional instructions and clarifications for the analysis_schema.

analysis_schema

object

When the call ends, the transcript and call details will be analyzed by the AI.Define a JSON schema for how you want to get information about the call - information like email addresses, names, appointment times or any other type of custom data.In the webhook response or whenever you retrieve call data later, you’ll get the data you defined back under analysis.For example, if you wanted to retrieve this information from the call:

{
"analysis_schema": {
    "email_address": "email",
    "first_name": "string",
    "last_name": "string",
    "wants_to_book_appointment": "boolean",
    "appointment_time": "YYYY-MM-DD HH:MM:SS"
}
}

You would get it filled out like this in your webhook once the call completes:

{
"analysis": {
    "email_address": "[email protected]",
    "first_name": "John",
    "last_name": "Doe",
    "wants_to_book_appointment": true,
    "appointment_time": "2024-01-01 12:00:00"
}
}

answered_by_enabled

boolean

default:"false"

If this is set to true, we process the audio from the start of the call to determine if it was answered by a human or a voicemail.In the call details or webhook response, you’ll see the answered_by field with the value human, unknown or voicemail.Notes for accuracy:

When answered_by is voicemail or human, that is nearly 100% accurate.
When it is unknown, try using text analysis by adding answered_by to your analysis_schema.

Response

status

string

Can be success or error.

call_id

string

A unique identifier for the call (present only if status is success).

batch_id

string

The batch ID of the call (present only if status is success).

message

string

A message explaining the status of the call.

errors

array

For validation errors, a detailed list of each field with an error and it’s error message.Example:

    {
    "status": "error",
    "message": "Invalid parameters",
    "errors": [
        "Missing required parameter: phone_number.",
        "Missing required parameter: task.",
        "Phone number must be a string or number.",
        "Task must be a string."
    ]
    }

{
  "status": "success",
  "message": "Call successfully queued.",
  "call_id": "9d404c1b-6a23-4426-953a-a52c392ff8f1",
  "batch_id": null
}

Basic

Calls

Inbound Numbers

Outbound Numbers

Voices

Custom Twilio Accounts

Campaigns

Batches

Headers

Body

Agent Parameters (Body)

Call Parameters (Body)

Response

Basic

Calls

Inbound Numbers

Outbound Numbers

Voices

Custom Twilio Accounts

Campaigns

Batches

​Headers

​Body

​Agent Parameters (Body)

​Call Parameters (Body)

​Response

Headers

Body

Agent Parameters (Body)

Call Parameters (Body)

Response