The phone number, Client identifier, or username portion of SIP address that made this call. Phone numbers are in E.164 format (e.g., +16175551212). Client identifiers are formatted client:name. If using a phone number, it must be a Twilio number or a Verified outgoing caller id for your account. If the to parameter is a phone number, from must also be a phone number. If to is sip address, this value of from should be a username portion to be used to populate the P-Asserted-Identity header that is passed to the SIP endpoint.

The phone number, SIP address, Client, TwiML App identifier that received this call. Phone numbers are in E.164 format (e.g., +16175551212). SIP addresses are formatted as sip:name@company.com. Client identifiers are formatted client:name. TwiML App identifiers are formatted app:<APP_SID>. Custom parameters may also be specified.

The URL we should call using the status_callback_method to send status information to your application.

The HTTP method we should use to call status_callback. Can be: GET and POST and defaults to POST.

A label for this participant. If one is supplied, it may subsequently be used to fetch, update or delete the participant.

The number of seconds that we should allow the phone to ring before assuming there is no answer. Can be an integer between 5 and 600, inclusive. The default value is 60. We always add a 5-second timeout buffer to outgoing calls, so value of 10 would result in an actual timeout that was closer to 15 seconds.

Whether to record the participant and their conferences, including the time between conferences. Can be true or false and the default is false.

Whether the agent is muted in the conference. Can be true or false and the default is false.

Whether to play a notification beep to the conference when the participant joins. Can be: true, false, onEnter, or onExit. The default value is true.

Whether to start the conference when the participant joins, if it has not already started. Can be: true or false and the default is true. If false and the conference has not started, the participant is muted and hears background music until another participant starts the conference.

Whether to end the conference when the participant leaves. Can be: true or false and defaults to false.

The URL that Twilio calls using the wait_method before the conference has started. The URL may return an MP3 file, a WAV file, or a TwiML document. The default value is the URL of our standard hold music. If you do not want anything to play while waiting for the conference to start, specify an empty string by setting wait_url to ''. For more details on the allowable verbs within the waitUrl, see the waitUrl attribute in the <Conference> TwiML instruction.

The HTTP method we should use to call wait_url. Can be GET or POST and the default is POST. When using a static audio file, this should be GET so that we can cache the file.

Whether to allow an agent to hear the state of the outbound call, including ringing or disconnect messages. Can be: true or false and defaults to true.

The maximum number of participants in the conference. Can be a positive integer from 2 to 250. The default value is 250.

Whether to record the conference the participant is joining. Can be: true, false, record-from-start, and do-not-record. The default value is false.

Whether to trim leading and trailing silence from the conference recording. Can be: trim-silence or do-not-trim and defaults to trim-silence.

The URL we should call using the conference_status_callback_method when the conference events in conference_status_callback_event occur. Only the value set by the first participant to join the conference is used. Subsequent conference_status_callback values are ignored.

The HTTP method we should use to call conference_status_callback. Can be: GET or POST and defaults to POST.

The recording channels for the final recording. Can be: mono or dual and the default is mono.

The URL that we should call using the recording_status_callback_method when the recording status changes.

The HTTP method we should use when we call recording_status_callback. Can be: GET or POST and defaults to POST.

The SIP username used for authentication.

The SIP password for authentication.

The region where we should mix the recorded audio. Can be:us1, us2, ie1, de1, sg1, br1, au1, or jp1.

The URL we should call using the conference_recording_status_callback_method when the conference recording is available.

The HTTP method we should use to call conference_recording_status_callback. Can be: GET or POST and defaults to POST.

Whether the participant is coaching another call. Can be: true or false. If not present, defaults to false unless call_sid_to_coach is defined. If true, call_sid_to_coach must be defined.

The SID of the participant who is being coached. The participant being coached is the only participant who can hear the participant who is coaching.

Jitter buffer size for the connecting participant. Twilio will use this setting to apply Jitter Buffer before participant's audio is mixed into the conference. Can be: off, small, medium, and large. Default to large.

The SID of a BYOC (Bring Your Own Carrier) trunk to route this call with. Note that byoc is only meaningful when to is a phone number; it will otherwise be ignored. (Beta)

The phone number, Client identifier, or username portion of SIP address that made this call. Phone numbers are in E.164 format (e.g., +16175551212). Client identifiers are formatted client:name. If using a phone number, it must be a Twilio number or a Verified outgoing caller id for your account. If the to parameter is a phone number, callerId must also be a phone number. If to is sip address, this value of callerId should be a username portion to be used to populate the From header that is passed to the SIP endpoint.

The Reason for the outgoing call. Use it to specify the purpose of the call that is presented on the called party's phone. (Branded Calls Beta)

The audio track to record for the call. Can be: inbound, outbound or both. The default is both. inbound records the audio that is received by Twilio. outbound records the audio that is sent from Twilio. both records the audio that is received and sent by Twilio.

The identifier of the configuration to be used when creating and processing the recording

The maximum duration of the call in seconds. Constraints depend on account and configuration.

Whether to detect if a human, answering machine, or fax has picked up the call. Can be: Enable or DetectMessageEnd. Use Enable if you would like us to return AnsweredBy as soon as the called party is identified. Use DetectMessageEnd, if you would like to leave a message on an answering machine. For more information, see Answering Machine Detection.

The number of seconds that we should attempt to detect an answering machine before timing out and sending a voice request with AnsweredBy of unknown. The default timeout is 30 seconds.

The number of milliseconds that is used as the measuring stick for the length of the speech activity, where durations lower than this value will be interpreted as a human and longer than this value as a machine. Possible Values: 1000-6000. Default: 2400.

The number of milliseconds of silence after speech activity at which point the speech activity is considered complete. Possible Values: 500-5000. Default: 1200.

The number of milliseconds of initial silence after which an unknown AnsweredBy result will be returned. Possible Values: 2000-10000. Default: 5000.

The URL that we should call using the amd_status_callback_method to notify customer application whether the call was answered by human, machine or fax.

The HTTP method we should use when calling the amd_status_callback URL. Can be: GET or POST and the default is POST.

Whether to trim any leading and trailing silence from the participant recording. Can be: trim-silence or do-not-trim and the default is trim-silence.

A token string needed to invoke a forwarded call. A call_token is generated when an incoming call is received on a Twilio number. Pass an incoming call's call_token value to a forwarded call via the call_token parameter when creating a new call. A forwarded call should bear the same CallerID of the original incoming call.

The STIR/SHAKEN passport for this call, provided as a base64 encoded string. Multiple passports (at max 5) are comma separated and provided as base64 encoded string

The URL that we should use to deliver push call notification.

The name that populates the display name in the From header. Must be between 2 and 255 characters. Only applicable for calls to sip address.

The emergency caller's GPS coordinates in decimal degrees format. Format: "latitude longitude" (space-separated)

• Latitude: decimal degrees, range -90.0 to +90.0 (negative for South, positive for North)
• Longitude: decimal degrees, range -180.0 to +180.0 (negative for West, positive for East)
• Precision: up to 6 decimal places recommended for meter-level accuracy

Note: If the value exceeds 150 characters, only the first 150 characters will be used.

The emergency caller's physical location description within a building or facility.

Note: If the value exceeds 20 characters, only the first 20 characters will be used.

The emergency caller's organization or entity name.

Note: If the value exceeds 20 characters, only the first 20 characters will be used.

The emergency caller's street address including street number and street name.

Note: If the value exceeds 60 characters, only the first 60 characters will be used.

The emergency caller's postal code or ZIP code.

Note: If the value exceeds 20 characters, only the first 20 characters will be used.

The emergency caller's city or municipality name. Should be the official city name as recognized by local authorities. Used in combination with state and country for emergency call routing.

Note: If the value exceeds 20 characters, only the first 20 characters will be used.

The emergency caller's state or province.

Note: If the value exceeds 20 characters, only the first 20 characters will be used.

The emergency caller's country. Currently supported US and CA only.

Note: If the value exceeds 20 characters, only the first 20 characters will be used.

The SID of the Account that created the Participant resource.

The SID of the Call the Participant resource is associated with.

The user-specified label of this participant, if one was given when the participant was created. This may be used to fetch, update or delete the participant.

The SID of the participant who is being coached. The participant being coached is the only participant who can hear the participant who is coaching.

Whether the participant is coaching another call. Can be: true or false. If not present, defaults to false unless call_sid_to_coach is defined. If true, call_sid_to_coach must be defined.

The SID of the conference the participant is in.

The date and time in GMT that the resource was created specified in RFC 2822 format.

The date and time in GMT that the resource was last updated specified in RFC 2822 format.

Whether the conference ends when the participant leaves. Can be: true or false and the default is false. If true, the conference ends and all other participants drop out when the participant leaves.

Whether the participant is muted. Can be true or false.

Whether the participant is on hold. Can be true or false.

Whether the conference starts when the participant joins the conference, if it has not already started. Can be: true or false and the default is true. If false and the conference has not started, the participant is muted and hears background music until another participant starts the conference.

The status of the participant's call in a session. Can be: queued, connecting, ringing, connected, complete, or failed.

The wait time in milliseconds before participant's call is placed. Only available in the response to a create participant request.

The URI of the resource, relative to https://api.twilio.com.