Real-time voice is no longer a novelty. Contact centers, apps, and devices now expect natural, low-latency dialogue that can answer questions, complete tasks, and hand off cleanly when a human is needed. The top companies for AI voice agent development combine strong speech tech with reliable orchestration so those conversations feel effortless — for the caller and for your engineers.

Choosing a partner starts with fit. Some teams want an API to spin up phone agents in minutes. Others need enterprise controls, on-prem options, or a design partner that can ship an entire product. This guide maps the landscape so you can find the best companies for AI voice agent development for your use case, budget, and compliance needs.

Best Companies For Real-Time AI Voice Agent Development

1. Impekable

Impekable builds tailored customer-service voice agents that sound natural and handle routine calls around the clock, blending Google Contact Center AI with Twilio and modern TTS. The team focuses on outcomes — faster deflection, lower support costs, and consistent caller experience — delivered through custom AI voice agent development that fits existing systems. Projects often pair Impekable’s product design DNA with ElevenLabs-powered generative voices for expressive speech.

Impekable is a small, senior, partner-led team that ships in tight loops and works directly with stakeholders. Its track record spans Fortune 500 programs, and partnerships with Google Cloud and Twilio de-risk deployment and shorten time to value. The result is a practical blend of design, engineering, and AI integration that holds up in production.

• Services and expertise: End-to-end software delivery, AI integration, Twilio communications, enterprise UI/UX, and custom AI voice agent development
• Location: San Francisco, California
• Team size: ~50 employees
• Portfolio: Google Cloud and Twilio partnerships; case studies across finance, retail, and more — examples include Nike, Netgear, Panasonic

2. OpenAI

OpenAI provides the intelligence backbone that many voice agents run on. Its GPT-realtime and Realtime Voice API handle speech-to-speech in one pipeline, so agents can listen and speak with minimal delay and more expressive prosody. If your team wants state-of-the-art language understanding with Whisper recognition and high-quality voices, OpenAI sits among the best AI voice agent development companies for core model capability.

The path to production is API-first. Developers can compose real-time streaming I/O, manage safety tools, and deploy across cloud environments — often paired with telephony providers and contact center stacks. OpenAI’s scale, research cadence, and thriving ecosystem shorten the distance from prototype to a reliable voice agent that behaves well under edge cases.

• Services and expertise: LLMs (GPT-5 family), Whisper speech-to-text, Realtime Voice API for speech-to-speech, developer-friendly cloud APIs
• Location: San Francisco, USA
• Team size: ~3,000 employees
• Portfolio: ChatGPT, GPT models, Whisper, image generation; widely integrated via partners including Microsoft Azure

3. Vapi

Vapi focuses squarely on the developer who wants a working phone agent today, not next quarter. Provide prompts and logic, attach a number, and the platform stitches together telephony, speech recognition, synthesis, and LLM orchestration. Strong defaults, minutes-to-live setup, and careful attention to latency make Vapi a favorite for support lines, schedulers, and outbound agents.

Under the hood, Vapi has processed 62M+ calls across 1M+ agents for a developer community topping 250,000. That usage pressure has matured the platform’s reliability and cost controls. If you need velocity — or to trial an agent before deeper integration — Vapi is often treated as a top AI voice agent development company for rapid iteration.

• Services and expertise: API/SDK for real-time voice agents; integrated STT, LLM dialogue, and TTS; templates for inbound/outbound bots with low latency
• Location: San Francisco, USA
• Team size: ~10 employees (lean startup with growing adoption)
• Portfolio: 62M+ calls handled; 1M+ agents launched across startups to Fortune 500 use cases

4. Google

Google covers both ends of voice — consumer and enterprise. Google Assistant set expectations for context, follow-ups, and device reach across more than a billion endpoints. On the enterprise side, Dialogflow and Contact Center AI power conversational IVR and live voice bots, while the newer “live” voice APIs combine recognition, generative dialogue, and speech in one stream, making Google a top pick among the best companies for AI voice agent development.

For teams that need language breadth and dependable infrastructure, Google’s Speech-to-Text and Text-to-Speech are proven at scale. Dialogflow CX brings tooling for complex flows and handoffs, and it plugs into telephony and CRMs without heavy lifting. Add Gemini-class models and you get a path to sophisticated, low-latency agents with enterprise guardrails.

• Services and expertise: Google Assistant; Dialogflow CX/ES; Speech-to-Text and Text-to-Speech; Contact Center AI on Google Cloud
• Location: Mountain View, USA, with global offices
• Team size: ~187,000 employees (Alphabet)
• Portfolio: Assistant on 1B+ devices; Dialogflow and CCAI widely used across Android, Nest, Auto, and third-party apps

5. Voximplant

Voximplant is CPaaS for teams that want programmable telephony and voice AI in one place. Engineers can script nuanced call flows, add Smart IVR, and connect to NLU engines such as Dialogflow or Watson. For many contact center leaders, the “Avatar” offering accelerates conversational voice bots across channels without rebuilding the plumbing.

Scale and reach are proven — 30,000+ customers and more than a billion calls per year. Its serverless logic and SIP/PSTN depth support complex routing, recording, and analytics while staying manageable for lean teams. If you’re mapping vendors by adoption and breadth, Voximplant frequently appears among the top companies for AI voice agent development.

• Services and expertise: Voice/video/messaging APIs; serverless telephony apps; Smart IVR; Avatar conversational bots; NLP integrations
• Location: Palo Alto, USA, with global presence (New York, London, Bogota)
• Team size: ~200 employees
• Portfolio: 30,000+ customers and 1B+ calls/year; used by brands such as KFC, Burger King, Hyundai, Rappi, and Leroy Merlin

6. NVIDIA

NVIDIA equips the builders behind many real-time voice systems. Riva — its GPU-accelerated ASR/TTS toolkit — lets teams deploy speech services with sub-second latency, on-prem or in cloud. If your constraints include data residency, cost per inference, or ultra-low latency, Riva’s microservices and GPU optimization provide a sturdy path to production.

Beyond Riva, NVIDIA’s GPUs accelerate training and inference for third-party voice models across sectors. From in-car assistants to healthcare dictation, teams build on CUDA, TensorRT, and a mature developer stack. Pairing the hardware with the Riva speech SDK gives engineering leaders tight control over latency, throughput, and unit economics at scale.

• Services and expertise: GPUs and AI software; Riva speech SDK for real-time ASR/TTS; tools for NLU and reference apps
• Location: Santa Clara, USA
• Team size: ~36,000 employees
• Portfolio: Riva deployed for virtual assistants, contact center transcription, and multilingual voices; NVIDIA GPUs power many speech pipelines

7. Retell AI

Retell AI replaces rigid call center scripts with AI-native voice agents you can set up without code. Agents handle natural turn-taking, follow multi-step instructions, and connect to calendars, CRMs, and external APIs. Teams use it to swap IVR trees for conversational flows that answer questions, qualify leads, and book appointments

Early deployments report strong economics — reductions in handling costs up to 80% and high caller satisfaction, backed by an NPS of 90. Start with a pilot, iterate in a visual builder, then scale traffic once flows stabilize. Retell’s quick setup and analytics appeal to operators who want measurable results without a long build cycle.

• Services and expertise: No-code voice agent builder for contact centers; conversational flows, escalation, and integrations to backend tools
• Location: San Francisco Bay Area, USA
• Team size: ~20 employees
• Portfolio: Deployments and pilots across education admissions, insurance, and healthcare with cost and wait-time reductions

8. Microsoft

Microsoft’s Azure stack brings speech, bots, and telephony together under one roof. Azure Speech handles recognition and Neural TTS; the Bot Framework structures conversations; Azure Communication Services ties it to phone numbers and PSTN. With tight integration to OpenAI models on Azure, teams can assemble real-time agents that respect enterprise security and compliance.

If your org lives in Microsoft 365, the benefits compound — logging, monitoring, identity, and data governance come out of the box. Many companies prefer Azure when procurement, privacy, and region placement guide vendor choice. For leaders staffing teams, Azure’s ecosystem also makes it easier to hire AI voice agent developers who already know the tooling.

• Services and expertise: Azure AI Speech, Bot Framework, and Communication Services; integrations with OpenAI models in Azure; enterprise cloud tooling
• Location: Redmond, USA, with global hubs
• Team size: ~228,000 employees
• Portfolio: Voice tech across Cortana’s legacy, Teams live transcription/translation, and Azure Voice Agent capabilities in preview

9. Amazon

Amazon popularized consumer voice with Alexa and backs it with industrial-scale infrastructure. For builders, AWS exposes the blocks behind Alexa: Amazon Lex for NLU and speech, Polly for lifelike TTS, Transcribe for recognition, and Amazon Connect for contact centers. That combination makes AWS a top AI voice agent development company for teams standardizing on a unified cloud.

Skills and integrations give you reach across homes, cars, and workplaces. Inside the enterprise, Connect flows with Lex and Lambda automate routing and self-service, while analytics track containment and wait times. Whether you’re adding a voice FAQ or modernizing a full IVR, AWS maps cleanly to both experiments and global rollouts.

• Services and expertise: Alexa ecosystem; AWS Lex, Polly, Transcribe; Amazon Connect for contact centers; enterprise integrations and skills
• Location: Seattle and Arlington (HQs), USA
• Team size: ~1,556,000 employees
• Portfolio: Alexa on tens of millions of devices; AWS voice services used across banking, hospitality, and automotive

10. Rasa

Rasa gives enterprises full control over conversational logic and deployment. As an open-source platform, it supports custom pipelines, on-prem hosting, and integration with your choice of STT/TTS — ideal when privacy and determinism matter. Rasa Voice focuses on real-time performance, turn-taking, and barge-in so assistants feel responsive while obeying business rules.

The community and enterprise support model is a strength. With millions of downloads and contributions from thousands of developers, Rasa has matured into a dependable base for assistants at telecoms, banks, and insurers. If you need auditability and the ability to harden flows, it’s a solid choice for high-stakes deployments.

• Services and expertise: Open-source conversational AI for text and voice; NLU, dialogue management, voice channel connectors; enterprise guardrails and on-prem options
• Location: San Francisco, USA (HQ) and Berlin, Germany
• Team size: ~145 employees
• Portfolio: Used by global enterprises across telecom, healthcare, finance, and insurance; recognized by industry analysts for flexibility and control

Choosing The Right Voice Agent Partner

Match the vendor to your constraint. If latency and speech quality are paramount, prioritize platforms with streaming speech-to-speech and proven telephony — think Google, OpenAI, Vapi, or Voximplant. If compliance and deployment control lead the conversation, NVIDIA with Riva or Rasa’s open-source stack give you knobs to tune. Shortlist three of the best AI voice agent development companies, build a thin vertical slice, and compare real-call metrics before you commit.

Look beyond the demo. Map pricing to your call mix, confirm failover paths, and test escalations to human agents. If you need a partner to own product execution, a consultancy like Impekable can deliver custom AI voice agent development end to end, while cloud platforms suit teams that prefer building in-house. With a clear pilot, realistic KPIs, and a plan for ongoing training data, your first real-time voice agent won’t just talk — it will deliver.

If you want to feature your company developing real-time AI voice agent solutions on this list, email us or submit a form in the Top Choices section. After a thorough assessment, we’ll decide whether it’s a valuable addition.