15 · voice-agent · 07 systems
Voice & phone agentsAgents that answer the phone — and make calls.
Voice agents handle real-time spoken conversations: inbound reception and support, outbound reminders and qualification, scheduling, intake, and surveys. The category is mostly developer platforms (Vapi, Retell, Bland, Deepgram, ElevenLabs Agents) that orchestrate speech-to-text, a model, and text-to-speech over telephony — plus no-code products (Synthflow) that ship a ready receptionist.
Systems in this category
Vapi
Vapi · voice-agent
Vapi is the developer platform for voice agents: API-first orchestration of STT, LLM, TTS, and telephony so you can put an agent on a phone number in minutes — and swap every layer.
Bland AI
Bland AI · voice-agent
Bland AI is the enterprise phone-agent platform: autonomous inbound/outbound calls at scale with an emphasis on security, compliance, and call-center-grade throughput.
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Retell AI
Retell AI · voice-agent
Retell AI is a voice-agent platform focused on production call quality: fine-grained latency tuning, interruption handling, and both API and no-code agent building for phone agents.
Synthflow
Synthflow · voice-agent
Synthflow is the no-code voice-agent product: agencies and SMBs build receptionist, intake, and outbound agents from templates without touching telephony or APIs.
ElevenLabs Agents
ElevenLabs · voice-agent
ElevenLabs Agents is the voice agent platform built on the industry's best-known TTS: conversational agents with top-tier voices, phone and web deployment, and model-agnostic reasoning.
Deepgram Voice Agent
Deepgram · voice-agent
Deepgram Voice Agent is the speech-native API: a single endpoint that combines Deepgram's STT/TTS with an LLM loop for real-time voice agents, priced per minute.
Grok Voice Agent API
xAI · voice-agent
Grok Voice Agent API is xAI's speech-to-speech platform for production voice agents — full-duplex turns under ~700ms, tool calling and live search mid-conversation, telephony via SIP or a provisioned number, plus a no-code Voice Agent Builder in beta.
Who it's for
Teams with real call volume — clinics, home services, logistics, restaurants, sales floors — plus developers embedding voice into a product that would otherwise need a call center.
Tradeoffs
Latency and barge-in handling separate demos from production; per-minute pricing stacks (platform + telephony + STT + LLM + TTS) and scales badly at volume; and disclosure/consent rules for automated calls vary by jurisdiction.
Frequently asked
What is a voice agent?
An agent that conducts live phone or audio conversations — transcribing speech, reasoning over it, and speaking back in a few hundred milliseconds. Unlike IVR trees, these hold open-ended conversations and take actions (booking, lookup, escalation) mid-call.
Who should use a voice agent?
Teams with real call volume — clinics, home services, logistics, restaurants, sales floors — plus developers embedding voice into a product that would otherwise need a call center.
What are the tradeoffs of voice agents?
Latency and barge-in handling separate demos from production; per-minute pricing stacks (platform + telephony + STT + LLM + TTS) and scales badly at volume; and disclosure/consent rules for automated calls vary by jurisdiction.
Which voice agents are in the catalog?
7 as of 2026-09-25: Vapi (Vapi), Bland AI (Bland AI), Retell AI (Retell AI), Synthflow (Synthflow), ElevenLabs Agents (ElevenLabs), Deepgram Voice Agent (Deepgram), Grok Voice Agent API (xAI).
Build on a platform or buy a product?
Platforms (Vapi, Retell, Deepgram) give you API control over the whole stack — pick your STT, model, voice, telephony — and suit teams shipping voice as a feature. Products like Synthflow package the receptionist end-to-end for businesses that just want calls answered.
Why is per-minute pricing stacked?
A voice call consumes several metered services at once: telephony minutes, speech-to-text, LLM tokens, text-to-speech characters, and the platform's orchestration fee. The headline rate (e.g., Vapi's ~$0.05/min) is only the orchestration layer — the real cost is the sum.