Features, pricing, and fit
Compare ConversationRelay and Voice Agent API on voice capabilities, pricing, and fit.
Compare Twilio ConversationRelay and Deepgram Voice Agent for AI phone agents, Voice AI platforms, then match channels, workflows, and deployment models to your call flow.
Programmable Voice component that connects a TwiML ConversationRelay session to an application WebSocket for STT/TTS, language settings, DTMF, and call events.
Developers building their own voice-agent logic while keeping telephony, media handling, and call control in Twilio.
Explore its buying criteria: AI phone agents · Voice AI platforms.
Unified Voice Agent API that combines Deepgram speech recognition, LLM orchestration, and voice synthesis with function calling and mid-session controls.
Developers who want one managed voice API instead of assembling separate STT, orchestration, and TTS services.
Explore its buying criteria: AI phone agents · Voice AI platforms.
Both profiles checked 2026-09-04.
Use the table below to compare each provider’s documented scope.
Before you decide
Twilio ConversationRelay: Usage-based Programmable Voice minutes and phone numbers, plus ConversationRelay per-minute charges; model, provider, and other call features are separate. Deepgram Voice Agent: Usage-based per-hour API pricing; the product page publishes $4.50/hour, with telephony separate. Ask both vendors to quote the same expected workload, required channels, and implementation scope. Include required subscriptions and usage charges before comparing the total; the listed starting prices alone may cover different work.
The recorded knowledge and data sources for Twilio ConversationRelay include Not publicly documented. For Deepgram Voice Agent, they include Not publicly documented. Ask each provider to demonstrate access for the exact systems you use, with permissions, freshness, and failure behavior. A source missing from this directory is not proof that a provider cannot support it.
Use the same representative calls, approved instructions, and escalation rules in both pilots. How does it handle interruption and uncertainty? Which actions can it complete, and which require approval? What context reaches a human during transfer? Record conversation quality, completed tasks, human handoffs, and total cost in the buyer worksheet. Check these specific cautions before launch: Twilio ConversationRelay: Not a packaged agent. Region, carrier, recording, compliance, model, and application responsibilities remain with the implementer. Deepgram Voice Agent: Telephony and complete workflow operations are not implied. Confirm languages, concurrency, pass-through charges, observability, and data controls.
Record your requirements and pilot results in the buyer worksheet →
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| Criterion | ConversationRelay | Voice Agent API |
|---|---|---|
| Provider type | Telephony voice-agent runtime | Voice agent API and speech infrastructure |
| Best fit | Developers building their own voice-agent logic while keeping telephony, media handling, and call control in Twilio. | Developers who want one managed voice API instead of assembling separate STT, orchestration, and TTS services. |
| Key capabilities | phone audio streaming; speech interface; interruptions; WebSocket protocol; TwiML controls | managed runtime; speech recognition; speech synthesis; bring-your-own LLM; functions |
| Team sizes | startup; mid-market; enterprise; developer | startup; mid-market; enterprise; developer |
| Call surfaces | phone / PSTN; WebSocket | WebSocket; web; mobile; telephony integrations |
| Voice stack | Cascaded speech interface with developer-supplied LLM | Cascaded STT-LLM-TTS managed full stack |
| Telephony | Twilio Programmable Voice; phone numbers; SIP | Not publicly documented |
| Call controls | Not publicly documented | Not publicly documented |
| Languages | Not publicly documented | Not publicly documented |
| Integrations | Not publicly documented | Not publicly documented |
| Knowledge and data | Not publicly documented | Not publicly documented |
| Pricing model | Usage-based Programmable Voice minutes and phone numbers, plus ConversationRelay per-minute charges; model, provider, and other call features are separate. | Usage-based per-hour API pricing; the product page publishes $4.50/hour, with telephony separate. |
| Pricing signal | ConversationRelay $0.07/min; US local outbound $0.014, inbound $0.0085, SIP $0.004, number $1.15/month. | $4.50/hour, equivalent to $0.075/min, plus telephony. |
| Free plan or trial | Not publicly documented | 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. | Deepgram’s documented API puts STT, LLM orchestration, TTS, barge-in, turn-taking, function calling, and session control behind one interface. |
| Considerations | Not a packaged agent. Region, carrier, recording, compliance, model, and application responsibilities remain with the implementer. | Telephony and complete workflow operations are not implied. Confirm languages, concurrency, pass-through charges, observability, and data controls. |
Developers building their own voice-agent logic while keeping telephony, media handling, and call control in Twilio.
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.
Developers who want one managed voice API instead of assembling separate STT, orchestration, and TTS services.
Deepgram’s documented API puts STT, LLM orchestration, TTS, barge-in, turn-taking, function calling, and session control behind one interface.
Verify current pricing, limits, security, and required integrations directly with each provider before purchasing.
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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