Features, pricing, and fit
Compare Realtime API and Voice Agent API on voice capabilities, pricing, and fit.
Compare OpenAI Realtime and Deepgram Voice Agent for AI phone agents, Voice AI platforms, then match channels, workflows, and deployment models to your call flow.
Model-level realtime API for text and audio input/output over WebRTC, WebSocket, or SIP, with function calling.
Product and engineering teams building a spoken application around a realtime model instead of a packaged contact-center product.
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
OpenAI Realtime: Token-based API pricing for text, audio, and image modalities; audio input/output rates are published per million tokens. 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 OpenAI Realtime 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: OpenAI Realtime: Not a turnkey contact center. Implement telephony operations, identity, tools, monitoring, evaluation, retention, and escalation. 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 →
Swipe or scroll the table to see every column.
| Criterion | Realtime API | Voice Agent API |
|---|---|---|
| Provider type | Native realtime multimodal model API | Voice agent API and speech infrastructure |
| Best fit | Product and engineering teams building a spoken application around a realtime model instead of a packaged contact-center product. | Developers who want one managed voice API instead of assembling separate STT, orchestration, and TTS services. |
| Key capabilities | audio-to-audio conversation; WebRTC; WebSocket; SIP; tools | 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 | WebRTC; WebSocket; SIP; API / SDK | WebSocket; web; mobile; telephony integrations |
| Voice stack | Native audio input/output with tool calling | Cascaded STT-LLM-TTS managed full stack |
| Telephony | SIP connection; carrier integration remains buyer responsibility | 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 | Token-based API pricing for text, audio, and image modalities; audio input/output rates are published per million tokens. | Usage-based per-hour API pricing; the product page publishes $4.50/hour, with telephony separate. |
| Pricing signal | GPT-Realtime audio $32 per million input audio tokens and $64 per million output audio tokens. | $4.50/hour, equivalent to $0.075/min, plus telephony. |
| Free plan or trial | Not publicly documented | Not publicly documented |
| What stands out | GPT-Realtime accepts and returns audio directly, while the Agents SDK supplies transport helpers plus tools, guardrails, handoffs, and session history. | Deepgram’s documented API puts STT, LLM orchestration, TTS, barge-in, turn-taking, function calling, and session control behind one interface. |
| Considerations | Not a turnkey contact center. Implement telephony operations, identity, tools, monitoring, evaluation, retention, and escalation. | Telephony and complete workflow operations are not implied. Confirm languages, concurrency, pass-through charges, observability, and data controls. |
Product and engineering teams building a spoken application around a realtime model instead of a packaged contact-center product.
GPT-Realtime accepts and returns audio directly, while the Agents SDK supplies transport helpers plus tools, guardrails, handoffs, and session history.
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
Your business. Your shortlist.
Start with your website. Answer a few focused questions, then get a personalized PDF with fit, trade-offs, alternatives and a pilot plan for your call flow.
