What's New?

1. Logs UX Refresh: New filter layout plus a round of UX improvements — improved date picker, active row is clearly highlighted across all log views when the flyout is opened, log tables are fully keyboard-accessible, sortable cost and duration columns, pagination, and more.

2. Squads contextEngineeringPlan Handoff Type — previousAssistantMessages: Forwards only the conversation history from before the current assistant’s session. The current assistant’s own messages and tool calls are excluded entirely from the handoff payload. See the updated handoff context configuration docs.

3. assistant.speechStarted Event — Live Captions & Word-Level Timing (GA): A new opt-in message fires as the assistant begins speaking each segment, carrying the full turn text, turn, source (model / force-say / custom-voice), and optional timing:

   • Per-word alignment on ElevenLabs
   • Cursor-based word-progress on Minimax (set voice.subtitleType: "word", with correct CJK handling)
   • Text-only fallback on all other providers

   Subscribe by adding "assistant.speechStarted" to your assistant’s clientMessages and/or serverMessages — now GA with no feature flag. Use it for live captions, karaoke-style highlighting, or any UI that needs to stay in sync with assistant audio. Fully backward-compatible; no existing messages changed.

4. Autofallbacks on Transcribers: Let Vapi pick the best transcriber to fall back to if your primary one fails — even mid-call. Opt in by setting assistant.transcriber.fallbackPlan.autoFallback.enabled to true. See the updated transcriber fallback plan docs.

1. Monitoring — GA: Automated call quality monitoring is now generally available. Detect issues with trigger-based rules, get alerts when something goes wrong, and surface resolution suggestions — all from the dashboard.

   • Monitoring quickstart
   • Announcement blog post

Here’s a summary of major items shipped from October 2025 through March 2026.

Platform

1. Squads v2: Visual builder to simplify sophisticated multi-assistant orchestration with seamless handoffs between specialized agents.

2. Composer (Alpha): Intelligent assistant inside the dashboard that allows you to describe what you need through plain text prompts to help build, adjust, and debug voice agents.

3. Simulations (Alpha): Voice agent testing feature to build confidence through enabling systematic, AI-powered testing in specific scenarios with evaluation of outcomes.

4. Monitoring & Issues: Automated call quality monitoring with trigger-based issue detection, alerting, and resolution suggestions.

5. HIPAA with Data Retention: New compliance mode with private storage and in-dashboard toggle/purchase flow — available for additional cost.

6. Zero Data Retention: Compliance mode that keeps context data during call as needed to execute tasks and retains no data afterwards.

7. Consolidated Logs: Unified log viewing into a single page.

8. Vapi Voices: 12 new ultra-realistic voices released, optimized for latency and cost with adjustable speed controls exposed. 8 legacy voices deprecated.

New Models & Provider Support

Transcriber Models (Speech-to-Text)

1. Deepgram Nova-3 Languages: Added Hebrew, Urdu, Tagalog, and Arabic bilingual support.

2. Cartesia Transcriber: ink-whisper.

3. Soniox: stt-rt-v4.

Intelligence Models (LLM)

1. GPT-5 Family: OpenAI’s latest intelligence models, including GPT-5, 5-Mini, 5-Nano, 5.1, 5.2, 5.4, 5.4-Mini, 5.4-Nano.

2. Claude 4.5–4.6: Anthropic’s latest intelligence models Sonnet 4.5, Opus 4.5, Opus 4.6, Sonnet 4.6.

3. Gemini 3 Flash: Google’s latest intelligence models.

4. Grok 4 Fast: Reasoning and non-reasoning variants.

5. GPT Realtime Mini: OpenAI’s lightweight realtime model.

Voice Models (Text-to-Speech)

1. Cartesia: sonic-3, sonic-3-2026-01-12, sonic-3-2025-10-27.

2. WellSaid: Caruso (new), legacy.

3. Inworld: inworld-tts-1 (REST, original), inworld-tts-1.5-max (WebSocket, $10/M chars), inworld-tts-1.5-mini (WebSocket, $5/M chars).

4. ElevenLabs Scribe v2: Latest version of ElevenLabs speech-to-text.

Developer Tools & API

1. Structured Outputs Improvements: Updates to our AI-powered analysis and data extraction tool, including transient structured outputs, audio-based extraction, and regex extraction.

2. SIP Request Tool + DTMF over SIP INFO: Send SIP requests and DTMF tones via SIP INFO messages during calls.

3. Variable Passing Between Tool Calls: Pass output variables from one tool call as input to subsequent tool calls.

4. Encrypted Tool Arguments: Encrypt sensitive tool arguments to protect data in transit.

5. Low Confidence Speech Hook: Hook that triggers when the transcriber returns low-confidence speech results.

6. Time Elapsed Hook: Hook that triggers at specified time intervals during a call.

7. assistant.speechStarted Event: New event fired when the assistant begins speaking.

8. MCP Improvements: Bearer auth, $ref dereferencing, child tool messages/discovery.

9. Warm Transfer Improvements: SIP support, caller ID, context engineering, variable filling.

1. Legacy Endpoint Removal: The following deprecated endpoints have been removed as part of our API modernization effort:

   • /logs - Use call artifacts and monitoring instead
   • /workflow/{id} - Access workflows through the main workflow endpoints
   • /test-suite and related paths - Replaced by the new evaluation system
   • /knowledge-base and related paths - Integrated into model configurations

2. Knowledge Base Architecture Change: The knowledgeBaseId property has been removed from all model configurations. This affects:

   • XaiModel, GroqModel, GoogleModel
   • OpenAIModel, AnthropicModel, CustomLLMModel
   • All other model provider configurations

3. Transcriber Property Deprecation: AssemblyAITranscriber.wordFinalizationMaxWaitTime and FallbackAssemblyAITranscriber.wordFinalizationMaxWaitTime are now deprecated:

   • Use smart endpointing plans for better speech timing control
   • More precise conversation flow management
   • Enhanced end-of-turn detection capabilities

4. Schema Path Cleanup: Removed numerous unused schema paths from model configurations to simplify the API structure and improve performance. This cleanup affects internal schema references but doesn’t impact your existing integrations.

5. New v2 API: We are introducing a new API version v2. These changes are part of our ongoing effort to:

   • Simplify the API structure for better developer experience
   • Remove redundant and deprecated functionality
   • Complete the transition to new evaluation and compliance systems
   • Improve API performance and maintainability

For details on the new features that replace these deprecated endpoints, see our recent changelog entries:

• Enhanced Authentication & Custom Credentials (Aug 30)
• Recording Consent & Compliance Management (Sep 2)
• Evaluation System Foundation (Sep 5)
• Evaluation Execution & Results Processing (Sep 28)

Migration Guide

Removed Endpoints

The following endpoints are no longer available:

• GET /logs - Use call artifacts instead
• GET /workflow/{id} - Use main workflow endpoints
• GET /test-suite, POST /test-suite - Use evaluation endpoints
• GET /test-suite/{id}, PUT /test-suite/{id}, DELETE /test-suite/{id} - Use evaluation management
• POST /test-suite/{testSuiteId}/run - Use evaluation runs
• GET /knowledge-base, POST /knowledge-base - Integrated into model configurations
• All related nested endpoints and operations

See Also:

• Authentication System Updates (Aug 30) - For credential management migration
• Recording Consent Features (Sep 2) - For compliance system details
• Enhanced Transcription (Sep 8) - For AssemblyAI timing alternatives

1. Evaluation Execution Engine: Run comprehensive assistant evaluations with EvalRun and CreateEvalRunDTO. Execute your mock conversations against live assistants and squads to validate performance and behavior in controlled environments.

2. Multiple Evaluation Models: Choose from various AI models for LLM-as-a-judge evaluation:

   • EvalOpenAIModel: GPT models including GPT-4.1, o1-mini, o3, and regional variants
   • EvalAnthropicModel: Claude models with optional thinking features for complex evaluations
   • EvalGoogleModel: Gemini models from 1.0 Pro to 2.5 Pro for diverse evaluation needs
   • EvalGroqModel: High-speed inference models including Llama and custom options
   • EvalCustomModel: Your own evaluation models with custom endpoints

3. Evaluation Results: Comprehensive result tracking with EvalRunResult:

   • status: Pass/fail evaluation outcomes
   • messages: Complete conversation transcript from the evaluation
   • startedAt and endedAt: Precise timing information for performance analysis

4. Target Flexibility: Run evaluations against different targets:

   • EvalRunTargetAssistant: Test individual assistants with optional overrides
   • EvalRunTargetSquad: Evaluate entire squad performance and coordination

5. Evaluation Status Tracking: Monitor evaluation progress with detailed status information:

   • running: Evaluation in progress
   • ended: Evaluation completed
   • queued: Evaluation waiting to start
   • Detailed endedReason including success, error, timeout, and cancellation states

6. Judge Configuration: Optimize evaluation accuracy with model-specific settings:

   • maxTokens: Recommended 50-10000 tokens (1 token for simple pass/fail responses)
   • temperature: 0-0.3 recommended for LLM-as-a-judge to reduce hallucinations

Evaluation Capabilities

1. Enhanced Beep Detection: Improve voicemail detection accuracy with CreateVoicemailToolDTO.beepDetectionEnabled specifically for Twilio-based calls. This feature detects the characteristic beep sound that indicates voicemail recording has started.

2. Workflow Voicemail Integration: Configure comprehensive voicemail handling in workflows with enhanced message and detection capabilities:

   • Workflow.voicemailMessage: Custom messages for voicemail scenarios (up to 1000 characters)
   • Workflow.voicemailDetection: Configurable detection methods for different providers

3. Assistant Voicemail Enhancement: Improved voicemail handling in assistant configurations with Assistant.voicemailMessage and Assistant.voicemailDetection for consistent behavior across all conversation types.

4. Multiple Detection Methods: Choose from various voicemail detection providers:

   • Google: GoogleVoicemailDetectionPlan for AI-powered detection
   • OpenAI: OpenAIVoicemailDetectionPlan for intelligent voicemail recognition
   • Twilio: TwilioVoicemailDetectionPlan for carrier-level detection
   • Vapi: VapiVoicemailDetectionPlan for integrated detection

5. Beep Detection for Call Flows: The new beep detection capability works specifically with Twilio transport, providing reliable voicemail identification when traditional detection methods may not be sufficient.

6. Voicemail Tool Configuration: Enhanced tool rejection and messaging capabilities ensure appropriate handling when voicemail is detected, with configurable responses based on your business requirements.

Voicemail Management Features

1. Variable Value Analytics: Gain deeper insights into your assistant performance with AnalyticsQuery.groupByVariableValue. Group analytics data by specific variable values extracted during calls for granular performance analysis.

2. Enhanced Grouping Options: Use VariableValueGroupBy to specify custom grouping criteria:

   • key: The variable value key to group by (up to 100 characters)
   • Combine with existing grouping options like assistantId, endedReason, and status

3. Multi-Dimensional Analysis: Create complex analytics queries by combining traditional grouping fields with variable values:

   • Group by assistant performance AND custom business metrics
   • Analyze conversation outcomes by extracted data points
   • Track success rates across different variable value segments

4. Advanced Query Capabilities: Enhanced AnalyticsQuery functionality enables sophisticated data analysis:

   • Multiple grouping dimensions for comprehensive insights
   • Variable-based segmentation for business intelligence
   • Custom metric tracking through extracted call variables

5. Business Intelligence Integration: Connect your call data to business outcomes by grouping analytics on:

   • Customer satisfaction scores extracted from calls
   • Product interest levels determined during conversations
   • Lead qualification status gathered through assistant interactions
   • Custom KPIs specific to your business logic

Analytics Enhancements

1. Twilio SMS Transport: Send chat responses directly via SMS using TwilioSMSChatTransport in CreateChatDTO.transport. This enables programmatic SMS conversations with your voice assistants, bridging the gap between voice and text communication.

2. SMS Session Management: Create new sessions automatically when using SMS transport by providing:

   • customer: Customer information for SMS delivery
   • phoneNumberId: SMS-enabled phone number from your organization
   • Automatic session creation when both fields are provided

3. LLM-Generated vs Direct SMS: Control message processing with TwilioSMSChatTransport.useLLMGeneratedMessageForOutbound:

   • true (default): Input processed by assistant for intelligent responses
   • false: Direct message forwarding without LLM processing for notifications and alerts

4. Enhanced Chat Creation: CreateChatDTO now supports sophisticated session management:

   • transport: SMS delivery configuration
   • sessionId: Use existing session data
   • Mutual exclusivity between sessionId and transport fields for clear session boundaries

5. OpenAI Responses Integration: Streamlined chat processing with OpenAIResponsesRequest supporting the same transport and squad integration features for consistent API experience.

6. Cross-Platform Continuity: Seamlessly transition between voice calls and SMS conversations within the same session, maintaining context and conversation history across communication channels.

SMS Communication Features

1. API Version 2 Introduction: Access enhanced functionality through new versioned endpoints while maintaining full backward compatibility:

   • /v2/call: Enhanced call management with new features and improved response formats
   • /v2/phone-number: Advanced phone number management with extended capabilities

2. Enhanced Pagination: Improved pagination controls across all endpoints with PaginationMeta enhancements:

   • createdAtGe and createdAtLe: Date range filtering for creation timestamps
   • Better sorting and filtering options for large datasets
   • Enhanced metadata for pagination state management

3. Workflow Message Configuration: Customize voicemail handling in workflows with CreateWorkflowDTO.voicemailMessage and CreateWorkflowDTO.voicemailDetection for comprehensive call flow management.

4. Credential Integration: Seamless credential management across all workflow and assistant configurations with enhanced credentials.items.discriminator.mapping.custom-credential support.

5. Transport Infrastructure: Foundation for advanced communication channels with improved transport configuration and management capabilities.

Infrastructure Improvements

1. Squad-Based Sessions: Organize your assistants into collaborative teams with Session.squad and Session.squadId. Sessions can now be associated with squads for team-based conversation management and coordinated assistant behavior.

2. Squad Chat Integration: Enable squad-based chat conversations using Chat.squad and Chat.squadId. This allows multiple assistants to participate in or be aware of chat contexts for more sophisticated conversation handling.

3. Enhanced Session Creation: Create squad-enabled sessions with CreateSessionDTO.squad and CreateSessionDTO.squadId, enabling persistent conversation contexts across multiple assistants and interaction types.

4. Chat Management by Squad: Filter and organize chats by squad membership using GetChatPaginatedDTO.squadId for better conversation management and team-based analytics.

5. Session Management by Squad: Query sessions by squad association with GetSessionPaginatedDTO.squadId, providing team-based session organization and management capabilities.

6. Full Message History: Control conversation context retention with ArtifactPlan.fullMessageHistoryEnabled. When enabled, artifacts contain complete message history even after handoff context engineering, preserving full conversation flow for analysis.

7. Transfer Records: Track warm transfer details with Artifact.transfers, providing comprehensive records of transfer destinations, transcripts, and status information for multi-assistant conversations.

Team Collaboration Features