Everything your
voice agents need.
Natural conversations, mid-call actions, built-in telephony, analytics, and a visual agent builder.
Voice & AI Models
Full-duplex audio, 32+ languages, and your choice of AI model — configured from the dashboard.
Call Experience
Every call aspect is configurable — greetings, noise suppression, mid-call actions, and transfers.
Knowledge & Intelligence
Knowledge base, call analytics, and automatic post-call analysis.
Channels & Reach
Web widget, phone numbers, SIP trunking, and outbound calling API.
Agent Builder
Build, test, and publish agents entirely from the dashboard.
Platform
Teams, security, admin tools, and a full developer platform.
Voice & AI Models
Full-duplex audio
Both sides talk simultaneously with graceful interruption handling.
- Real-time turn-taking with configurable interruption sensitivity
- Minimum word threshold before allowing caller interruptions
- Turn detection with 23-language support and ~12ms inference
Natural personality
Listening cues like "uh-huh" and subtle office ambience for realism.
- Configurable acknowledgment word list and frequency
- Pre-synthesized cues at session start for zero latency
- Background audio (e.g., call-center ambience) with adjustable volume
Dozens of voices
OpenAI, ElevenLabs, and AWS Polly with accent, gender, and speed options.
- OpenAI TTS: gpt-4o-mini-tts with 10 voices (alloy, ash, ballad, coral, echo, fable, nova, onyx, sage, shimmer)
- ElevenLabs: v3 and Flash 2.5 with dynamically fetched premade and professional voices
- AWS Polly: generative and neural engines (Danielle, Matthew, Ruth, etc.)
32+ languages
Multilingual voice support across all providers out of the box.
- Configurable language per agent for STT, TTS, and LLM independently
- Polyglot voices on Nova Sonic support 7 languages simultaneously
- Voice best practices injection optional per language
Traditional pipeline
GPT-4.1 / GPT-5 + Deepgram STT + TTS for maximum flexibility.
- LLM: GPT-4.1, GPT-4.1-mini, GPT-4.1-nano, GPT-4o, GPT-4o-mini, GPT-5, GPT-5-mini, GPT-5-nano, GPT-5.1, GPT-5.2
- STT: Deepgram Nova-3 with configurable language
- TTS: OpenAI, ElevenLabs, or AWS Polly — mix and match providers
Speech-to-speech
Nova Sonic 2.0, OpenAI Realtime, Gemini Live, Grok — ultra-low latency.
- AWS Nova Sonic 2.0: 16 voices, 7 languages, configurable endpointing (LOW/MEDIUM/HIGH)
- OpenAI Realtime: gpt-realtime and gpt-4o-realtime-preview, semantic VAD with eagerness levels
- Google Gemini Live: 30 voices (Puck, Charon, Kore, Fenrir, etc.), 59+ languages
- Grok Voice Agent: 5 voices (Ara, Rex, Sal, Eve, Leo), 40+ languages, server-side VAD
Per-agent tuning
Temperature, turn detection, and silence thresholds per agent.
- Temperature from 0 to 2 (default 1.0) for creativity vs. determinism
- Smart turn detection with configurable activation threshold and silence duration
- Dynamic system prompts with template variables resolved at call start
Call Experience
Configurable greetings
AI-generated, pre-defined message, or silent mode.
- Dynamic: AI generates greeting from system prompt context
- Static: pre-defined message (e.g., "Hi, I am Kelly...")
- Silent: agent waits for the caller to speak first
Noise suppression
Deep-learning noise cancellation for clearer conversations.
- DTLN deep-learning noise cancellation plugin
- Configurable strength from 0 (off) to 1 (maximum)
- Applied to caller audio for clearer agent comprehension
Cost & spam controls
Max duration, silence hangup, and inactivity reminders.
- Inactivity reminders with configurable interval (e.g., 10-15s) and max count
- Max call duration up to 1 hour (3,600,000ms)
- End call after configurable silence timeout (180s-600s)
- Configurable ring duration before timeout (default 30s)
Look up information
Query any system for order status or account details mid-call.
- Custom HTTP tools with configurable method, headers, body, and timeout
- Response variables capture values via JSONPath extraction
- Values injected into conversation context for follow-up use
Book appointments
Real-time availability via Calendly and Cal.com.
- Calendly integration with event type URI and timezone configuration
- Cal.com integration with full availability checking
- Real-time slot availability and instant booking confirmation
Call any API
HTTP endpoints with configurable auth and request templates.
- Configurable HTTP method, headers, auth, body templates, and query params
- Body templates with {{variable}} placeholders resolved at call time
- Supports JSON and SOAP/XML response parsing
- Strict JSON schema compliance mode for function calls
Transfer calls
Zero-gap audio handoff to humans or external numbers.
- Cold transfer via SIP REFER for zero-audio-gap handoff
- Transfer to human agents or external phone numbers
- Transfer destination automatically logged in call record
Agent-to-agent transfer
Hand off a live call to a different AI agent with a completely new persona.
- New agent fully takes over — different voice, LLM, prompt, tools, and knowledge base
- Caller stays on the same line with no interruption
- Configurable context passing: full conversation history, AI-generated summary, or fresh start
- Multiple transfer targets per agent — route to billing, support, or sales based on conversation
- New agent greets the caller using its own voice and personality
- Transfer tracked in call logs with target agent link
Voicemail detection
Detect machines and leave messages or generate AI responses.
- Automatic answering machine detection (CPA/AMD)
- Three actions: hang up, send static message, or LLM-generated message
- Audio resampled 48kHz to 8kHz with G.711 ULAW encoding
- Available on outbound calls only
Knowledge & Intelligence
Multiple sources
Crawl web pages, upload PDFs / Word docs, or paste text.
- URL crawling with auto-discovery of linked pages, include/exclude path patterns
- PDF and Word document upload with size tracking
- Direct text input with custom titles
Auto-refresh
Scheduled re-crawling keeps web content current.
- Configurable re-crawl interval per URL source
- Automatic status tracking: pending, processing, completed, failed
- Error messages and progress details per source
Vector search
Semantic retrieval with automatic chunking and deduplication.
- OpenAI text-embedding-3-small (1536d) or AWS Bedrock (256d)
- Automatic content chunking with token counting and metadata
- Content hashing for deduplication across sources
- Full-text keyword search fallback alongside semantic search
Analytics dashboard
Volume trends, performance, daily costs, disconnection analysis.
- Call volume trends (line chart), calls by agent (bar chart)
- Sentiment and outcome distribution (pie/bar charts)
- Cost per day with consolidated cost/duration metrics
- Disconnection reason analysis and agent performance comparison
Full call detail
Transcript, audio, cost breakdown, latency, and event timeline.
- Transcript with speaker labels and tool call visibility
- Audio playback synced to transcript — click to seek, auto-highlight during playback
- Cost breakdown: LLM input/output tokens, TTS characters, STT minutes
- Latency metrics: LLM TTFT, TTS TTFB, end-to-end delay
- Events timeline, raw logs, dynamic variables, KB retrieval URLs
Post-call analysis
Automatic summary, sentiment, success evaluation, and outcome.
- Call summary (1-3 sentences) and success evaluation (boolean)
- Sentiment: Positive / Negative / Neutral / Unknown
- Outcome: Contained / Partially Contained / Business Rule Transfer / Early Abandon / Hangup / Agent Escalation / Confusion Transfer / Timeout
- Configurable analysis model and custom analysis prompts
Custom extraction
Define additional data points to extract per agent.
- Per-agent fields with types: string, boolean, enum, number
- Extracted automatically from transcript after each call
- Results available via API, dashboard, and webhooks
Webhooks
call_started, call_ended, call_analyzed events with auto retry.
- Configurable URL with timeout per webhook
- Automatic retry logic with delivery tracking
- Response logging for debugging integrations
Channels & Reach
Web widget
Voice or chat on any website — floating bubble or inline embed.
- Modes: voice-only, chat-only, or voice + chat simultaneously
- Display: bubble (floating button + panel) or inline (embedded in page)
- Real-time audio streaming via WebRTC
- Try the embed demo
Fully customizable
Colors, themes, icons, branding, and per-page overrides. White-label ready.
- Theme: light / dark / auto with accent color (hex)
- Position, visualizer type (aura/wave), layout (side-by-side/stacked)
- Custom bubble icon and label, panel width and height
- Control visibility: microphone, chat, and leave button toggles
- White-label: toggle Blowfish branding off per embed
- Security: allowed origins (CORS), rate limiting, Cloudflare Turnstile bot protection
Number marketplace
Search, purchase, and manage phone numbers from the dashboard.
- Twilio integration for search, purchase, and management
- Filter by region/country with E.164 validation
- Assign numbers to agents with inbound/outbound direction tracking
SIP trunking
Inbound/outbound trunks with IP or credential authentication.
- Inbound: IP-based (allowed addresses) or credential-based (username/password) auth
- Outbound: configurable SIP server, transport (UDP/TCP/TLS/WS/WSS), phone number pool
- Custom headers and metadata per trunk
Dispatch rules
Route incoming calls to agents by trunk and phone number.
- Route by trunk, inbound number, and metadata
- Rule types: individual routing (to agent) or direct routing (to trunk)
- Auto-cleanup: outbound trunk deleted when last number removed
Outbound API
Launch calls with per-call prompt, greeting, and metadata overrides.
- E.164 format for from_number and to_number
- Per-call agent override, greeting, prompt, goodbye, voicemail behavior
- Metadata and dynamic variables injected at call start
- Form-based key/value builder alongside raw JSON mode
Agent Builder
Visual configuration
Voice, model, prompt, tools, knowledge, and telephony in one place.
- Voice catalog organized by provider, gender, accent, age with language filtering
- LLM catalog by provider, type (traditional vs. S2S), and billing model
- STT catalog with language support metadata
Draft & publish
Edit freely without affecting live agents, publish with one click.
- Draft/published state machine for safe editing
- Published configs synced to production cache for instant reads
- Cron job keeps configs in sync across environments
Dynamic prompts
Template variables like {{caller_name}} resolved at call start.
- Variables: {{caller_name}}, {{current_time_{{timezone}}}}, {{user_number}}, {{franchise_id}}
- Resolved at call start from metadata and system context
- Can reference values captured from previous tool calls
Browser testing
Push-to-talk or open-mic with support for test variables.
- Push-to-talk button alongside open-mic mode
- Pass custom variables to simulate real call metadata
- Full transcript and tool call visibility during test
Voice preview
Listen to voice samples before choosing.
- Cached voice samples with signed URLs for instant playback
- Listen directly in the voice selector
- Organized by provider, gender, accent, and age
Retell migration
Import wizard maps existing Retell agents, prompts, and voices.
- Automatic mapping of agents, prompts, tools, voices, and dynamic variables
- Provider and voice matching across platforms
- One-click migration from Retell AI
Platform
Org-based isolation
Each org sees only its own agents, calls, numbers, and data.
- Organization-scoped agents, calls, numbers, and knowledge bases
- Self-service org creation from the dashboard with org switching
- Cross-tab logout synchronization across browser sessions
Auth & roles
Email/password, magic link, Google SSO, admin/member RBAC.
- Email/password, magic link (passwordless), and Google SSO
- Email verification and password reset flows
- Admin and member roles with settings restrictions
- Signup approval workflow: pending, approved, or rejected
Super admin
Manage all orgs, user impersonation with audit trail.
- Dashboard to manage all organizations and users across the platform
- User impersonation with required reason, session expiration, and revocation
- Audit log: auth events, admin actions, user activity with IP and user agent
REST API & docs
Full API with interactive OpenAPI reference.
- CRUD endpoints for agents, calls, numbers, KBs, telephony, webhooks, voices, LLMs, embeds
- Auto-generated OpenAPI reference with interactive API explorer
- Internal API for secure agent-to-dashboard communication
MCP server
AI assistants can manage agents, calls, and numbers.
- List agents, get call details, list phone numbers, make outbound calls
- OAuth 2.1 provider: AI assistants authenticate via standard OAuth flow
- Connect to third-party MCP servers with per-server auth and timeout
Webhooks & cron
Call event subscriptions with retry and automated background jobs.
- Events: call_started, call_ended, call_analyzed
- Configurable URL, timeout, delivery tracking, automatic retry
- Automated background jobs: stale call cleanup, KB refresh, config sync
Ready to ship your first voice agent?
Deploy a production voice agent in minutes. Speech-to-speech or traditional pipeline — your choice.