TwiML Changelog

Changes in the Programmable Voice TwiML functionality will be documented here for your reference.

TwiML - 2023.06.01

We are beginning to roll out updates to our Voice TwiML processor. Some changes that may impact your call flows are:

• Some inbound calls which were previously marked as completed if the first verb was not <Hangup> or <Reject> will now be marked as no-answer or busy as determined by the verb
• We will no longer use the same cookies for HTTP webhook requests made between parent and child calls
• Cookies will not be shared between TwiML webhook URLs and status callback URLs for a given call SID
• Cookies will be collected during standalone <Play> responses, but will not be collected for <Play> verbs nested inside <Gather>
• We will now send silent RTP during the <Pause> verb; previously no RTP was sent from Twilio while the <Pause> verb executes
• We will now send silent RTP during the <Record> verb; previously no RTP was sent from Twilio while the <Record> verb executes
• Parameter overrides for Voice SDK calls can only override the To parameter

Dial - 2022.10.07

Answering machine detection (AMD) can now be enabled when creating child calls using <Dial><Number> and <Dial><Sip>, or when creating a new conference participant via POST to the /Participants API for accounts with Enhanced Programmable SIP Features enabled.

AMD will run in the background while the call connects and will return the results of our detection to inform your application when a human or machine answered, or when the voicemail message beep has been detected.

Dial - 2021.05.13

We are changing the behavior of <Dial> for accounts which have enabled Enhanced Programmable SIP Features. This could represent a breaking change for some call flows. If your account has not enabled Enhanced Programmable SIP Features, this does not represent a change.

The changes are:

• If a <Dial> action url is specified, Twilio will make a request to the provided action callback when the parent call is transferred to a new TwiML via call modification
• If no <Dial> action url is specified, the parent call will continue to the next verb in the current TwiML document when the parent call is modified to use new TwiML. Note: in most cases the verb after the <Dial> will not be executed since the call has been modified, but if the next verb is <Redirect> Twilio will make a request to the provided URL.

This change brings Enhanced Programmable SIP Feature enabled accounts behavior in alignment with the behavior of TwiML for non-enabled accounts.

Dial - 2020.12.09

Functional improvements

When Enhanced Programmable SIP Features are enabled on an account, the following functional improvements to <Dial> TwiML verb are available:

• <Dial> now allows simultaneous or sequential dialing to up to ten <Number>, <Client> or <Sip> endpoints in a single <Dial> command
• <Dial> now supports Global Low Latency (GLL) when using <Dial hangupOnStar=”true”>.
• A new action callback parameter DialBridged is added with value returned as true only if the call was bridged with the parent. This is to distinguish the cases where the child call was hung up during screening vs bridged with the parent.
  • The <Sip> noun now supports the ringTone parameter.
  • When sending status callbacks for a dialed leg, the geographic data specified in the webhook data will be for the To and From phone numbers of the dialed leg. Previously, the geographic data for the To and From numbers of the parent leg was used in the status callbacks for the dialed leg as well.
• Early audio will always be generated for the following scenarios
  • if simultaneous dialing is used, irrespective of the Early Audio Exception account flag
  • If the url attribute is present
  • If the sendDigits attribute is present

Changes that could impact your application

• Each dial leg in case of simultaneous and sequential dialing will now have its own call record. Previously only the completed call had a call-record created, which means you couldn't see data or signaling for the legs that were not answered. The new behavior also lets you cancel individual dial legs through the API.
• This new behavior should allow for more accurate records.
• This new behavior allows for more effective debugging.
• <Dial> verb will never be allowed in the TwiML returned by the screening url.
• In case of <Hangup> or <Reject> in screening url, DialCallStatus will be set to completed, previously it was set to no-answer.
• This is a more accurate representation of the call behavior, as the call connects and is rejected by the application
• This new behavior allows for more effective debugging.
• Cookies set on parent call TwiML responses will not be included in requests made to status callback URLs on child calls
• Changes to call status for inbound calls:
• With <Dial answerOnBridge="true">, parent call status will be ringing until the screening url is complete. Previously it was set to in-progress immediately.
• Child call status will be ringing until answered and in-progress when screening. Previously it was set to queued until answered.
• With <Dial answerOnBridge="true">, the parent call will report a status of no-answer until and unless it is bridged to the child call.
• This new behavior should allow for more accurate call tracking in customer applications.
• In case of hang up during screening, DialCallStatus will be set to completed. Previously DialCallStatus was set to no-answer.