For AI agents: a documentation index is available at the root level at /llms.txt and /llms-full.txt. Append /llms.txt to any URL for a page-level index, or .md for the markdown version of any page.
AcademyContact SalesHelp CenterDashboard
DocumentationAPI ReferenceIntegrationsAdministrationChangelog
DocumentationAPI ReferenceIntegrationsAdministrationChangelog
LogoLogo
AcademyContact SalesHelp CenterDashboard

Changelog

Stay up to date with the latest changes to Synthflow.
April 14, 2026
April 14, 2026

In-call SMS and WhatsApp messaging

Voice agents can now send SMS or WhatsApp messages during a live call and feed the customer’s reply back into the conversation as a variable. This is useful for capturing details that are hard to relay by voice — one-time passcodes, email addresses, invoice IDs, links, and short menus of options.

  • Two new action types, INCALL_SMS and INCALL_WHATSAPP, attachable to a voice agent under the During phase.
  • Blocking or non-blocking reply handling with a configurable timeout and fallback message.
  • Replies are injected into the call transcript and exposed as {sms_reply} / {whatsapp_reply} variables.
  • Requires a connected Twilio account; in-call WhatsApp additionally requires a linked WhatsApp sender.

See the In-Call Messaging guide.

EndpointChange
POST /actionsAccepts INCALL_SMS and INCALL_WHATSAPP action types.
PUT /actions/{action_id}Accepts INCALL_SMS and INCALL_WHATSAPP action types.
GET /actions/{action_id}action_type may be INCALL_SMS or INCALL_WHATSAPP.
GET /actionsaction_type may be INCALL_SMS or INCALL_WHATSAPP.
Was this page helpful?
Previous

April 13, 2026

Next
Built with