Schemas

CreateCallRequest

To

string · pattern: ^\+?[0-9]{7,15}$ · required

Destination phone number. E.164 format, or 7 to 15 digits with an optional leading plus sign.

Example: +2348031234567

From

string · pattern: ^\+?[0-9]{7,15}$ · required

Caller ID to originate the call from. Must be a phone number your Signals project owns; an unowned number returns error 21210.

Example: +2342013300100

Url

string · uri

Absolute http(s) URL fetched for a OneML document once the call connects. Required unless Twiml is given. If both Url and Twiml are present, Url is used and Twiml is ignored.

Example: https://voice.example.com/oneml/answer

Twiml

string · maxLength: 4000

Inline OneML document to run instead of fetching Url. Ignored if Url is also present. Must parse as valid OneML, or the request fails with error 12100.

Example: <Response><Say>Your verification code is 4 8 2 9 1 6.</Say></Response>

Method

string · enum

HTTP method used to fetch Url. Any value other than GET is treated as POST.

Enum values:

GET

POST

Example: POST

Default: POST

StatusCallback

string · uri

Absolute http(s) URL notified about call status changes.

Example: https://voice.example.com/status-callback

StatusCallbackMethod

string · enum

HTTP method used to call StatusCallback. Any value other than GET is treated as POST.

Enum values:

GET

POST

Example: POST

Default: POST

StatusCallbackEvent

string[]

Call lifecycle events that trigger StatusCallback. Repeat the parameter to request more than one event. Defaults to ["completed"] when omitted or empty. Other values are accepted but never match an emitted event.

Enum values:

initiated

ringing

answered

completed

Example: ["initiated","completed"]

Default: ["completed"]

Timeout

integer · min: 1 · max: 600

Seconds to let the destination ring before the call is treated as unanswered. Values outside 1 to 600 are clamped rather than rejected.

Example: 60

Default: 60

CallerId

string · pattern: ^\+?[0-9]{7,15}$

Overrides the caller ID presented on this call. Must be a phone number your project owns (error 21210) and in the same format as To and From (error 13214).

Example: +2342013300101

TimeLimit

integer

Maximum call duration in seconds, measured from answer.

Example: 3600

SendDigits

string · maxLength: 32 · pattern: ^[0-9A-Da-d#*wW]{0,3…

DTMF digits to play after the call connects. At most 32 characters from 0-9, A-D, a-d, #, *, w and W (w inserts a 0.5 second pause).

Example: 1234#

ApplicationSid

string

Not supported. Providing ApplicationSid always fails the request with error 21605; use Url or Twiml instead. A Signals voice application ID is not accepted here either.

Example: AP0123456789abcdef0123456789abcdef

UpdateCallRequest

Exactly one of Url, Twiml, or Status is required. Method requires Url.

Url

string · uri

Absolute HTTP or HTTPS OneML URL for an in-progress call.

Example: https://voice.example.com/oneml/transfer

Method

string · enum

Enum values:

GET

POST

Default: POST

Twiml

string · maxLength: 4000

Inline OneML for an in-progress call.

Example: <Response><Hangup/></Response>

Status

string · enum

completed ends an in-progress call; canceled requires a call that has not answered.

Enum values:

completed

canceled

oneOf

Exactly one variant must match.

Decision Table

Variant	Matching Criteria
	type = object · requires: Url
	type = object · requires: Twiml
	type = object · requires: Status

Properties for Variant 1:

Url

string · uri · required

Absolute HTTP or HTTPS OneML URL for an in-progress call.

Example: https://voice.example.com/oneml/transfer

Method

string · enum

Enum values:

GET

POST

Default: POST

Twiml

string · maxLength: 4000

Inline OneML for an in-progress call.

Example: <Response><Hangup/></Response>

Status

string · enum

completed ends an in-progress call; canceled requires a call that has not answered.

Enum values:

completed

canceled

Call

sid

string

Unique identifier of this call.

Example: CA5388f7a5e04d0ed71cac5cdf1ea17a53

account_sid

string

SID of the Voice Account that owns this call.

Example: AC9ce1cd445308e3ec5080c6126288aa09

api_version

string

date_created

string

RFC 2822 formatted creation timestamp.

Example: Thu, 02 Jul 2026 12:00:00 +0000

date_updated

string

RFC 2822 formatted last-update timestamp.

Example: Thu, 02 Jul 2026 12:00:05 +0000

annotation

string | null

Reserved. Always null.

Example: null

answered_by

string | null

Reserved for answering-machine detection. Always null.

Example: null

caller_name

string | null

Reserved for caller name lookup. Always null.

Example: null

direction

string

Call direction, for example inbound, outbound-api or outbound-dial.

Example: outbound-api

duration

string | null

Call duration in seconds. Null until the call has ended and been recorded.

Example: 45

end_time

string | null

RFC 2822 formatted end timestamp. Null until the call ends.

Example: Thu, 02 Jul 2026 12:00:50 +0000

forwarded_from

string | null

Reserved. Always null.

Example: null

from

string

from_formatted

string

Identical to from.

Example: +2342013300100

group_sid

string | null

Reserved. Always null.

Example: null

trunk_sid

string | null

Reserved. Always null.

Example: null

parent_call_sid

string | null

SID of the call that created this one, when applicable.

Example: null

queue_time

string

Milliseconds the call waited between being queued and initiated. "0" when not applicable.

Example: 0

phone_number_sid

string | null

SID of the number used for this call, when known.

Example: PN9992109eed74a671cdc4e192a934d43e

price

string | null

Price field reported by the voice engine. Signals charges for the call appear in Signals usage, not in this field.

Example: null

price_unit

string | null

Currency of price.

Example: null

start_time

string | null

RFC 2822 formatted answer timestamp. Null until the call is answered.

Example: Thu, 02 Jul 2026 12:00:05 +0000

status

string · enum

Current call status.

Enum values:

queued

ringing

in-progress

completed

busy

no-answer

canceled

failed

Example: in-progress

object

Paths of resources related to this call.

to

string

to_formatted

string

Identical to to.

Example: +2348031234567

uri

string

Path of this call resource.

Example: /2010-04-01/Accounts/AC9ce1cd445308e3ec5080c6126288aa09/Calls/CA5388f7a5e04d0ed71cac5cdf1ea17a53.json

CallList

Call[]

uri

string

Path of this request, without query parameters.

Example: /2010-04-01/Accounts/AC9ce1cd445308e3ec5080c6126288aa09/Calls.json

page

integer

Current page number.

Example: 0

page_size

integer

Calls per page.

Example: 50

first_page_uri

string

Path of the first page.

Example: /2010-04-01/Accounts/AC9ce1cd445308e3ec5080c6126288aa09/Calls.json?page=0&page_size=50

next_page_uri

string

Path of the next page. Omitted when there are no more results.

Example: /2010-04-01/Accounts/AC9ce1cd445308e3ec5080c6126288aa09/Calls.json?page=1&page_size=50

previous_page_uri

string

Path of the previous page. Omitted on the first page.

Example: /2010-04-01/Accounts/AC9ce1cd445308e3ec5080c6126288aa09/Calls.json?page=0&page_size=50

Recording

sid

string

Unique identifier of this recording.

Example: REd947fbd985d13ecb4c31eca3186f20bb

account_sid

string

SID of the Voice Account that owns this recording.

Example: AC9ce1cd445308e3ec5080c6126288aa09

call_sid

string

SID of the call this recording was captured during.

Example: CA5388f7a5e04d0ed71cac5cdf1ea17a53

duration

integer

Recording duration in seconds. Omitted until the recording finishes.

Example: 42

format

string

Media format of the recording, for example wav. Omitted until known.

Example: wav

date_created

string · date-time

ISO 8601 creation timestamp.

Example: 2026-07-02T12:00:00Z

date_updated

string · date-time

ISO 8601 last-update timestamp.

Example: 2026-07-02T12:00:42Z

uri

string

Path of this recording resource.

Example: /2010-04-01/Accounts/AC9ce1cd445308e3ec5080c6126288aa09/Recordings/REd947fbd985d13ecb4c31eca3186f20bb.json

RecordingList

Recording[]

uri

string

Path of this request. This list is not paginated.

Example: /2010-04-01/Accounts/AC9ce1cd445308e3ec5080c6126288aa09/Calls/CA5388f7a5e04d0ed71cac5cdf1ea17a53/Recordings.json

CallEventList

CallEvent[] · required

start

integer · required

Zero-based position of the first event on this page.

Example: 0

end

integer · required

Zero-based position of the last event on this page, or start when the page is empty.

Example: 1

page

integer · required

page_size

integer · required

uri

string · required

Path of this page.

Example: /2010-04-01/Accounts/AC9ce1cd445308e3ec5080c6126288aa09/Calls/CA5388f7a5e04d0ed71cac5cdf1ea17a53/Events.json?PageSize=50&Page=0

first_page_uri

string · required

next_page_uri

string | null · required

Path of the next page, or null on the last page.

Example: null

previous_page_uri

string | null · required

Path of the previous page, or null on the first page.

Example: null

CallEvent

object · required

object

Your server's response. Omitted when no response was received.

TwilioError

Error body returned by the voice engine for create-call failures.

code

integer

Twilio-compatible numeric error code.

Example: 21205

message

string

Human-readable error description.

Example: A valid 'Url' (absolute http(s)) or 'Twiml' must be provided.

more_info

string · uri

Reference URL for the error code.

Example: https://www.twilio.com/docs/errors/21205

status

integer

HTTP status code of the response.

Example: 400

Problem

Error document for errors that Signals raises itself.

type

string · uri · required

title

string · required

status

integer · required

detail

string · required

code

string · required

Stable machine-readable error code.

Example: voice_route_not_proxied

request_id

string · required

Identifier of this request, also returned in the X-Request-ID header.

Example: req_0192f3a4b5c67d8e9f0a1b2c3d4e5f60