Retell AI vs OpenAI Realtime API

Comparing the features of Retell AI to OpenAI Realtime API

Feature
Retell AI
OpenAI Realtime API

Capability Features

Agent Builder
Agent Testing
API Access
Appointment Scheduling
Auto-Sync Knowledge Base
Automatic Scalability
Millions of concurrent calls
Batch Calls
Branded Caller ID
Call History
Call Monitoring
Call Transfer Options
Edge Case Handling
Enterprise Privacy Commitment
Expanded Model Support Planned
Five New Voices
5
Function Calling
Global Reach
Human and Automated Safety Monitoring
Industry Compliance
SOC 2 Type 1&2HIPAAGDPR
Interruption Handling
LLM-Powered
Low Latency
500ms latency
Multi-language Support
18+ languages
Multiple Deployment Channels
AI phone callsWeb callsSMSChat
Natural Language Conversations
Navigate Through IVR
No Concurrency Limits
No Training on Data Without Permission
Platform Uptime
99.99% uptime
Playground Access
Prompt Caching Planned
Public Beta
Reference Client Available
Six Preset Voices
6
Speech-to-Speech
Streaming Audio Inputs/Outputs
Supports Text and Audio Inputs
TextAudio
Ultra Low Latency
Verified Phone Numbers
Voicemail Detection
WebSocket Connection

Integration Features

Agora Integration
Chat Completions API Integration
CRM/Automation Integrations
Cal.comn8nGoHighLevelTwilioVonageOpenAI
Integrates with Any CRM
Integrates with Any Telephony
Integrates with Automation Platforms
Integrates with Databases
LiveKit Integration
OpenAI Node.js SDK Planned
OpenAI Python SDK Planned
Supports GPT-4o
gpt-4o-realtime-preview
Telephony Integration
TwilioVonageTelnyxPlivoRingCentral
Twilio Voice API Integration

Limitation Features

AI Disclosure Requirement
Audio Only Modality (Initially)
Lower Session Limits Tiers 1-4
Lower than 100
No Desktop App Mentioned
No Mentioned Self-hosting
No Public Pricing Listed
No Simultaneous Session Limit Anymore
Simultaneous Sessions Limit Tier 5
100
Usage Policy Restriction

Pricing Features

Approximate Audio Input Price
$0.06/minute
Approximate Audio Output Price
$0.24/minute
Free Tier
No Free Tier
Pricing Audio Input
$100/1M tokens
Pricing Audio Output
$200/1M tokens
Pricing Cached Audio Input
$20/1M tokens
Pricing Cached Text Input
$2.50/1M tokens
Pricing Plan Details
Pricing Text Input
$5/1M tokens
Pricing Text Output
$20/1M tokens