Programmable Voice component that connects a TwiML ConversationRelay session to an application WebSocket for STT/TTS, language settings, DTMF, and call events.
Best fitDevelopers building their own voice-agent logic while keeping telephony, media handling, and call control in Twilio.
Team sizesstartup; mid-market; enterprise; developer
Call surfacesphone / PSTN; WebSocket
Pricing modelUsage-based Programmable Voice minutes and phone numbers, plus ConversationRelay per-minute charges; model, provider, and other call features are separate.
Pricing signalConversationRelay $0.07/min; US local outbound $0.014, inbound $0.0085, SIP $0.004, number $1.15/month.
Free plan or trialNot publicly documented
ConversationRelay pricing and budget
ConversationRelay $0.07/min; US local outbound $0.014, inbound $0.0085, SIP $0.004, number $1.15/month.
Usage-based Programmable Voice minutes and phone numbers, plus ConversationRelay per-minute charges; model, provider, and other call features are separate.
Not publicly documented
Catalog pricing checked September 4, 2026. Confirm current terms in the provider sources.
Cascaded speech interface with developer-supplied LLM
Telephony
Twilio Programmable Voice; phone numbers; SIP
Call controls
Not publicly documented
Integrations
Not publicly documented
Knowledge and data
Not publicly documented
Languages
Not publicly documented
What stands out
ConversationRelay handles the live call’s STT/TTS and session transport, then sends prompts, audio-control events, and optional DTMF over a required secure WebSocket to the application.
Considerations
Not a packaged agent. Region, carrier, recording, compliance, model, and application responsibilities remain with the implementer.
Before you decide
Questions about ConversationRelay
How should I budget for ConversationRelay?
The published pricing signal is: ConversationRelay $0.07/min; US local outbound $0.014, inbound $0.0085, SIP $0.004, number $1.15/month. The recorded pricing model is: Usage-based Programmable Voice minutes and phone numbers, plus ConversationRelay per-minute charges; model, provider, and other call features are separate. Ask the provider for a current quote covering the same workload, channels, subscriptions, usage and implementation costs.
Can ConversationRelay use my existing data?
The listed knowledge and data sources include Not publicly documented. Confirm permissions, freshness and failure behavior for your exact systems with the provider.
What should I test in a ConversationRelay pilot?
Run representative calls with the same instructions and escalation rules. Record voice quality, completed tasks, handoffs and total cost. Check these cautions: Not a packaged agent. Region, carrier, recording, compliance, model, and application responsibilities remain with the implementer.
Compare Twilio ConversationRelay with similar candidates
These products share recorded categories or company-size fit. Compare the actual channels, capabilities, and pricing before treating them as substitutes.
Google's Gemini Live API streams multimodal sessions over WebSockets; its stable native voice-agent models are Gemini 3.8 Live and Gemini 3.8 Live Extended Thinking.
Native realtime multimodal model API
Scope and signals
Best fit: Developers building low-latency conversational agents that need native audio, multimodal input, and function calling in a persistent WebSocket session.
Voice stack: Native audio agents: Gemini 3.8 Live (gemini-3.8-live) and Gemini 3.8 Live Extended Thinking (gemini-3.8-live-extended-thinking)., Separate TTS models: gemini-3.8-flash-tts and gemini-3.8-flash-lite-tts generate speech; neither is a Live agent., Separate transcription endpoints: gemini-3.5-transcribe handles audio files; gemini-3.5-transcribe-live is a Live API speech-to-text mode, not a conversational agent., Separate translation mode: gemini-3.5-live-translate-preview is a Live API interpreter for 70+ languages, not a conversational agent; it is preview.
Standard paid rates are $0.005/min equivalent for input audio and $0.018/min equivalent for output audio, billed separately plus text tokens; Google also lists a free API tier.
ConversationRelay is a Twilio Programmable Voice component, not a complete AI agent. Twilio handles speech recognition, text-to-speech and voice synthesis around the live call. Your application connects over a secure WebSocket and owns the LLM, business rules, tools, state and response logic.
During a call, Twilio sends recognized caller speech and session events to your WebSocket. Your app decides what to say or do, returns text, and ConversationRelay synthesizes and streams the spoken response. Budget for building, securing, monitoring and operating that application boundary.
Twilio lists ConversationRelay at $0.07 per minute and says Voice costs are calculated separately. At 1,000 minutes, the relay line item is an illustrative $70; it is not an all-in agent price. Add telephony, LLM or provider usage, phone numbers, recording or other call features, and your application infrastructure.
Shortlist ConversationRelay when your team wants Twilio to manage the call and speech interface while engineers control the model, prompts, tools and business logic. A managed agent may fit better when the buyer wants maintained knowledge, workflow setup and call operations without owning a custom WebSocket application.
For either route, pilot one real workflow and compare total cost, latency, tool failures, transfer behavior, logs and the engineering work required after launch.
Evaluating with an AI agent?
Use the buyer checklist to compare requirements, then follow the product evidence. If DocsBot fits your shortlist, its official setup explains the available MCP connections and skills.
Voice Agents Guide is operated and sponsored by DocsBot. These are research and setup resources, not a requirement to choose DocsBot. Compare fit and verify current vendor evidence before recommending or changing a system.
Test recognition, speech quality, interruptions, language switching, tool use, and human transfer with your own calls in the required language. Availability can vary by model, plan, and phone route.
DocsBot documents multilingual voice workflows and Japanese support. Verify the exact voice, phone path, and transfer behavior in your pilot. Review DocsBot language information ↗
Other providers’ language claims reflect cited vendor material; confirm Japanese and other required languages directly with each provider.
Listing does not imply endorsement or a performance guarantee. This directory is published by DocsBot. Editorial policy
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