Lead Qualification
Instantly screen inbound contacts, confirm match criteria, and log results.
00:00
A monday.com company
Two voice AI infrastructure platforms side by side, with Harmony.ai as the complete managed solution for teams handling 500+ calls a month. Every fact comes from the vendors’ own sites and docs.
Name
Work email
Phone Number
Vapi vs ElevenLabs vs Harmony.ai
 |  |  | |
|---|---|---|---|
| Platform | |||
| Built for | Developer platform for building voice agents, API-first | Voice infrastructure vendor: speech models plus a developer platform for building agents | Revenue teams: AI receptionist, AI SDR, scheduling |
| Model | Bring your own: choose the LLM and TTS provider per agent | General-purpose LLMs (Gemini, GPT, Claude) or bring your own; ElevenLabs' own speech models on top | Our own models, built for the phone |
| Sounds human | Bring-your-own TTS: ElevenLabs, PlayHT, Cartesia and others, plus your own cloned voices | Market-reference voices: 5,000+ voices in 31 languages, expressive v3 models; conversation logic is whatever LLM you pick | Our own conversation models handle interruptions, timing and tone, so calls feel human |
| Implementation | Self-serve; enterprise deployment support on Scale plan | Self-serve; build your first agent in five minutes (published) | White-glove |
| Calling & scale | |||
| Latency | Sub-500ms average (published) | Speech model ~75ms to ~280ms (published) plus a general-purpose LLM turn of ~600ms on Gemini Flash: roughly 700ms to 900ms end to end (our estimate; ElevenLabs publishes no call-level figure) | Sub-400ms median response |
| Concurrency | 10 concurrent included, $10 per line/month extra; custom on Scale | 4 to 40 concurrent calls by plan; burst to 3x at double the rate; elevated on Enterprise | 1 to 10,000 parallel calls |
| Telephony | Up to 5 free US numbers with daily outbound caps; import Twilio, Vonage or Telnyx numbers or bring a SIP trunk to scale | Twilio integration or SIP trunking; numbers come from your telephony provider, billed at cost | Built-in telephony or bring your own trunks; buy, assign and retire numbers across regions from one inventory; port or forward |
| Spam remediation | Docs walk you through registering STIR/SHAKEN and CNAM with your own carrier; nothing managed | Not offered; caller-ID reputation is left to your telephony provider | Number-reputation monitoring, automatic quarantine of flagged numbers, remediation, branded caller ID and local presence |
| IVR, screeners and gatekeepers | DTMF keypad tool for IVR menus, voicemail detection with fallback providers; nothing documented for human gatekeepers | Keypad touch-tone tool for IVR menus and voicemail detection with optional message; nothing documented for human gatekeepers | Navigates external phone trees, hold queues and human gatekeepers to reach the right party; DTMF both ways; voicemail detection and retry |
| Insight & improvement | |||
| Reporting | Analytics dashboard and API with custom queries; call logs and transcripts | Conversation history, evaluation criteria and data collection, analytics dashboard | Funnel, call-flow and conversation analytics on 100% of calls; ask for a report in plain language and get it built on the spot |
| Self-improvement | Manual: review calls, edit the assistant, re-run test suites | Manual: edit the agent, re-run tests and evals | Reasoning trace on every call, simulate changes on past calls, agent proposes knowledge-base updates you approve |
| Experimentation | Test suites and evals for regression testing; no built-in traffic-split A/B documented | Agent tests, simulations and evals; branches and environments for staged releases; no traffic-split A/B documented | A/B live or synthetic traffic, publish the winner, roll back; agent keeps what converts across a campaign |
| Pricing & compliance | |||
| Pricing | $0.05/min platform fee plus model costs at cost; HIPAA add-on $2,000/mo | $0.08 to $0.10 per call minute by plan, LLM and telephony billed at cost; enterprise custom | Plans start at $3K/month |
| Compliance | SOC 2, HIPAA (paid add-on), PCI | SOC 2, GDPR; HIPAA on Enterprise with eligible LLMs | SOC 2 Type II, HIPAA, GDPR, ISO 27001 |
Vapi and ElevenLabs figures from vapi.ai, docs.vapi.ai, elevenlabs.io and elevenlabs.io/docs, checked 9 Sep 2026. Vapi and ElevenLabs are trademarks of their owners. Harmony.ai is not affiliated with either.
Hear it on your own use case.
Four quick questions, then we’ll configure an agent on your use case and let you listen before you commit to anything.
Built for revenue, not a toolkit
Inbound and outbound on one platform. The agent dials, qualifies, and books meetings in your CRM.
Implementation is included
White-glove setup, live in days. No engineering project to stand up telephony, models, and workflows.
Every call becomes data
Every call transcribed and scored. Warm transfers with context, PII redaction, TCPA and DNC aware.
Scale without a quota request
1 to 10,000 parallel calls. Sub-400ms median response at any volume.
Meet Siena, your AI assistant
Enterprise-grade security
Enterprise-grade AI infrastructure with built-in protection and security, data privacy, governance, permissions, and compliance.
