Register Phone Call

Authorizations

Authorization

string

header

required

Authentication header containing API key (find it in dashboard). The format is "Bearer YOUR_API_KEY"

Body

application/json

agent_id

string

required

The agent to use for the call.

direction

enum<string>

Direction of the phone call. Stored for tracking purpose.

Available options:

inbound,

outbound

from_number

string

The number you own in E.164 format. Stored for tracking purpose.

metadata

object

An arbitrary object for storage purpose only. You can put anything here like your internal customer id associated with the call. Not used for processing. You can later get this field from the call object.

retell_llm_dynamic_variables

object

Add optional dynamic variables in key value pairs of string that injects into your Retell LLM prompt and tool description. Only applicable for Retell LLM.

to_number

string

The number you want to call, in E.164 format. Stored for tracking purpose.

Response

201 - application/json

agent_id

string

required

Corresponding agent id of this call.

call_id

string

required

Unique id of the call. Used to identify in LLM websocket and used to authenticate in audio websocket.

call_status

enum<string>

required

Status of call.

registered: Call id issued, starting to make a call using this id.
ongoing: Call connected and ongoing.
ended: The underlying websocket has ended for the call. Either user or agent hanged up, or call transferred.
error: Call encountered error.

Available options:

registered,

ongoing,

ended,

error

call_type

enum<string>

required

Type of the call. Used to distinguish between web call and phone call.

Available options:

phone_call

direction

enum<string>

required

Direction of the phone call.

Available options:

inbound,

outbound

from_number

string

required

The caller number.

to_number

string

required

The callee number.

call_analysis

object

Post call analysis that includes information such as sentiment, status, summary, and custom defined data to extract. Available after call ends. Subscribe to call_analyzed webhook event type to receive it once ready.

call_cost

object

Cost of the call, including all the products and their costs and discount.

disconnection_reason

enum<string>

The reason for the disconnection of the call. Read details desciption about reasons listed here at Disconnection Reason Doc.

Available options:

user_hangup,

agent_hangup,

call_transfer,

voicemail_reached,

inactivity,

machine_detected,

max_duration_reached,

concurrency_limit_reached,

no_valid_payment,

scam_detected,

error_inbound_webhook,

dial_busy,

dial_failed,

dial_no_answer,

error_llm_websocket_open,

error_llm_websocket_lost_connection,

error_llm_websocket_runtime,

error_llm_websocket_corrupt_payload,

error_frontend_corrupted_payload,

error_twilio,

error_no_audio_received,

error_asr,

error_retell,

error_unknown,

error_user_not_joined,

registered_call_timeout

end_timestamp

integer

End timestamp (milliseconds since epoch) of the call. Available after call ends.

latency

object

Latency tracking of the call, available after call ends. Not all fields here will be available, as it depends on the type of call and feature used.

latency.e2e

object

End to end latency (from user stops talking to agent start talking) tracking of the call. This latency does not account for the network trip time from Retell server to user frontend. The latency is tracked every time turn change between user and agent.

latency.knowledge_base

object

Knowledge base latency (from the triggering of knowledge base retrival to all relevant context received) tracking of the call. Only populated when using knowledge base feature for the agent of the call.

latency.llm

object

LLM latency (from issue of LLM call to first speakable chunk received) tracking of the call. When using custom LLM. this latency includes LLM websocket roundtrip time between user server and Retell server.

latency.llm_websocket_network_rtt

object

LLM websocket roundtrip latency (between user server and Retell server) tracking of the call. Only populated for calls using custom LLM.

latency.s2s

object

Speech-to-speech latency (from requesting responses of a S2S model to first byte received) tracking of the call. Only populated for calls that uses S2S model like Realtime API.

latency.tts

object

Text-to-speech latency (from the triggering of TTS to first byte received) tracking of the call.

metadata

object

opt_out_sensitive_data_storage

boolean

Whether this call opts out of sensitive data storage like transcript, recording, logging.

public_log_url

string

Public log of the call, containing details about all the requests and responses received in LLM WebSocket, latency tracking for each turntaking, helpful for debugging and tracing. Available after call ends.

recording_url

string

Recording of the call. Available after call ends.

retell_llm_dynamic_variables

object

Add optional dynamic variables in key value pairs of string that injects into your Retell LLM prompt and tool description. Only applicable for Retell LLM.

start_timestamp

integer

Begin timestamp (milliseconds since epoch) of the call. Available after call starts.

telephony_identifier

object

Telephony identifier of the call, populated when available. Tracking purposes only.

transcript

string

Transcription of the call. Available after call ends.

transcript_object

object[]

Transcript of the call in the format of a list of utterance, with timestamp. Available after call ends.

transcript_with_tool_calls

object[]

Transcript of the call weaved with tool call invocation and results. It precisely captures when (at what utterance, which word) the tool was invoked and what was the result. Available after call ends.

Call (V2)

Batch call

LLM

Agent

Phone Number

Knowledge Base

Voice

Account

Custom Telephony

Custom LLM

Register Phone Call

Authorizations

Body

Response