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OpenAI Realtime API vs Vapi
OpenAI Realtime API is positioned as speech-to-speech API for developers implementing their own voice application. Vapi is positioned as a developer-oriented orchestration platform for phone and web agents with configurable provid
OpenAI Realtime API is positioned as speech-to-speech API for developers implementing their own voice application. Vapi is positioned as a developer-oriented orchestration platform for phone and web agents with configurable providers. Start by deciding who owns the missing layers, then inspect the documented differences below.
Developer Frameworks and Full Platforms are different product categories. An underlying engine or framework is not a complete substitute for a deployed agent workflow.
12 jointly documented catalog fields. This measures evidence coverage, not equivalent quality or an overall winner.
Test opening hours, booking conflicts and an unanswered transfer.
Start where the records differ.
Values and evidence states are compared together. Shared facts follow the differences; Unknown never means No.
| Decision point | OpenAI Realtime API | Vapi |
|---|---|---|
| Billing modelDifferent records | component-stack | platform-plus-pass-through |
| Billing unitDifferent records | 1 million text/audio/image tokens; transcription separately metered | minute |
| Bring your telephonyDifferent records | Yes | Yes |
| Bring your modelDifferent records | Unknown | Yes |
| Warm transferDifferent records | Unknown | Yes |
| HIPAA pathDifferent records | Unknown | Yes |
Your requirements & next steps
Your requirements
Ready-made / AI receptionist · Strict evidence mode
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Realtime model tokens plus input transcription, tools and carrier/hosting; not GPT-Live session-minute billing.
Reviewed current public offer; retain original billing scope and units.
Cached audio/text and image inputs have separate rates. Rate is not per-minute.
Reviewed current public offer; retain original billing scope and units.
Model scope fixed to GPT-Realtime-2, not all voice models.
Reviewed current public offer; retain original billing scope and units.
Published Realtime token rates do not establish these account/contract terms. GPT-Live duration billing and unrelated fine-tuning discounts must not be imported.
Reviewed current public offer; retain original billing scope and units.
Published Realtime token rates do not establish these account/contract terms. GPT-Live duration billing and unrelated fine-tuning discounts must not be imported.
Reviewed current public offer; retain original billing scope and units.
Published Realtime token rates do not establish these account/contract terms. GPT-Live duration billing and unrelated fine-tuning discounts must not be imported.
Reviewed current public offer; retain original billing scope and units.
Repeated context, cache behavior and turn count affect token charges.
Reviewed current public offer; retain original billing scope and units.
Not yet researched against this buyer-critical field standard.
Reviewed current public offer; retain original billing scope and units.
Full bill requires measured model/token/cache/tool/carrier usage; conversation minutes alone are insufficient.
Provider choices, tokens, carrier and optional support/compliance fees are not fixed by minutes alone.
Full bill requires measured model/token/cache/tool/carrier usage; conversation minutes alone are insufficient.
Research conclusion about cost completeness, not a vendor capability.
Anyone with this link can view the encoded decision criteria.
Vendor documentation establishes a claim. Public model benchmarks are separate context, not measurements of these platforms.
Open saved comparison ↗What to verify together.
OpenAI Realtime API
A token rate cannot be compared directly with a bundled call-minute price.
GPT-Realtime-2 audio input $32/M, audio output $64/M; text input $4/M, output $24/M · V3.3 evidence review · GPT-Realtime-2 input audio tokens only; output/audio/text/cache have different rates; not 2.1 rate evidence
Excluded / confirm: Complete cost cannot be established from this reference. Full bill requires measured model/token/cache/tool/carrier usage; conversation minutes alone are insufficient. · Input transcription, tool/backend calls, carrier and application infrastructure
Realtime model tokens plus input transcription, tools and carrier/hosting; not GPT-Live session-minute billing.
Vapi
The $0.05 hosting charge is only one component of the call bill.
$0.05/min Vapi hosting · V3.3 evidence review · Hosting only; model, speech, carrier and compliance/support add-ons extra
Excluded / confirm: Complete cost cannot be established from this reference. Provider choices, tokens, carrier and optional support/compliance fees are not fixed by minutes alone. · LLM, transcriber, voice and carrier charges; HIPAA add-on $2,000/month
Reviewed current public offer; retain original billing scope and units.
The evidence overlap.
Both records have documented values for Product type, Technical setup, Pricing model, Published numeric pricing, Realtime / streaming audio, OpenAI models, MCP tools, Function / tool calling, Interruption controls, Official product documentation, Checked within 30 days, Retained price snapshot. Matching availability does not measure behavior under your call conditions.
Run the same booking, tool failure and unsuccessful human-transfer cases. Record both outcomes and billable units before signing a deployment agreement.
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