The best AI tools for building voice agents

The AI voice ecosystem is rich with powerful AI tools. With Deepgram for real-time, multilingual transcription, ElevenLabs for lifelike speech, and GPT-4o for responsive, multimodal reasoning, the possibilities for natural, rich AI-powered conversations are endless. Each is best in its class, and together, they can power natural, intelligent voice agents that feel almost human.

But choosing the right tools is just the beginning. Building with them in production requires powerful, dedicated infrastructure, seamless orchestration, and tight control over data and latency. This is where most developers run into friction.

In this guide, we’ll break down the best AI tools for voice and show you how Telnyx helps teams use them in one place without middlemen or compromises.

What are some of the best AI tools for voice?

The voice AI landscape is defined by specialized tools, each dominating a slice of the voice stack whether that’s transcription, speech synthesis, voice cloning, or LLM orchestration. These tools are not interchangeable. They’re best-in-class because of their raw performance, expressive range, or multimodal capabilities. Here’s a closer look at the top tools pushing the field of voice AI forward.

Speech-to-text

Whisper (OpenAI)

Whisper is OpenAI’s automatic speech recognition system, trained on 680,000 hours of multilingual audio. Known for its robustness across accents, background noise, and real-world audio, Whisper has become a go-to for developer teams building global voice agents. Though it lacks built-in diarization or low-latency streaming out of the box, its open-source availability makes it highly adaptable for custom applications.

Deepgram Nova 2 and Nova 3

Deepgram has become one of the fastest and most accurate speech-to-text (STT) providers in production environments. Nova 2 and 3 offer real-time transcription with incredibly low word error rates, support for over 30 languages, and features like speaker labeling, utterance timestamps, and emotion detection. Nova 3 also improves context retention, making it ideal for customer service and agent handoff scenarios. It’s widely regarded as a leader in commercial STT performance.

Text-to-speech

ElevenLabs v3

ElevenLabs set a new bar for natural, expressive speech synthesis. Their v3 engine supports 70+ languages and adds emotion tags like [excited] or [whispering] to enhance delivery. ElevenLabs also provides one of the most accessible and accurate voice cloning APIs, used in gaming, content creation, and AI agents. With human-like prosody, it’s a standout text-to-speech (TTS) engine for real-time applications.

Telnyx NaturalHD

NaturalHD, Telnyx’s in-house TTS engine, is specifically built for real-time voice applications. It generates expressive, human-like speech with subtle conversational cues like filler words and soft laughter. As it runs directly on Telnyx’s private, GPU-backed infrastructure, it is a flexible, cost-effective option, perfect for teams seeking low-latency, scalable solutions with full deployment control.

LLM Orchestration

Modern LLMs are now multimodal, memory-aware, and capable of contextual reasoning. These models are essential for powering intelligent voice agents. Here are the top performers:

• GPT-4o (OpenAI): Multimodal, responsive, and optimized for real-time interaction. It supports vision, audio, and long context windows, making it ideal for conversational agents.
• Claude 3 (Anthropic): Known for contextual reasoning and safety alignment. Claude is popular for customer support and enterprise applications that demand reliability.
• Gemini (Google DeepMind): Multilingual, image-aware, and tuned for structured reasoning, RAG, and retrieval-based workflows.
• LLaMA 3 (Meta): Open-source, fast, and efficient. It’s ideal for teams that want to self-host and fine-tune LLMs for private or custom logic.
• Qwen (Alibaba): Qwen-1.5 and 2.0 models are climbing the open-source leaderboards for coding, reasoning, and multilingual performance. The Qwen2-72B variant is one of the top-performing open LLMs on benchmarks like MMLU, GSM8K, and HumanEval. Hosted on Telnyx infrastructure, it regularly updates and is best for low-latency performance.

Voice cloning

MiniMax-Speech

MiniMax-Speech is a multilingual, zero-shot TTS model built for voice cloning. It requires just seconds of input to generate realistic speech in 32 languages. With competitive mean opinion scores (MOS) and low word error rates (WER), it’s become a research favorite for developers seeking lightweight, general-purpose TTS with impressive performance. Its rapid voice synthesis speed makes it viable for low-latency applications.

VALL-E

Developed by Microsoft Research, VALL-E is a neural codec language model that generates speech from text using just a three-second audio sample. It preserves emotional tone, speaker identity, and prosody. While still largely research-stage, its zero-shot capabilities represent a powerful foundation for personalized voice applications, especially when combined with real-time inference infrastructure.

Why these best AI tools stand out

Each of these tools excels in a specific domain of voice or language. Together, they form the core of next-gen conversational AI.

• Accuracy and naturalness: Whisper and Deepgram lead in speech recognition performance. ElevenLabs and MiniMax create highly natural speech output.
• Multilingual capability: All tools mentioned above support dozens of languages, which is essential for global deployments.
• Expressiveness and cloning: Tools like Telnyx NaturalHD, ElevenLabs, and VALL-E capture tone, pacing, and personality, sounding incredibly humanlike.
• Contextual reasoning: Modern LLMs are multimodal and memory-aware, which makes interactions more intelligent and useful.

These tools represent the peak of performance in their domains, and they’re only improving.

Combine the best AI tools with Telnyx

Choosing the right tools is one thing, but running them in production where real-time latency, uptime, and compliance matter, is another challenge altogether.

With Telnyx, you get:

• An orchestration layer that brings STT, TTS, and LLMs together.
• Built-in AI tools to make Voice AI Agents optimized for cost, speed, and accuracy.
• Telnyx NaturalHD voices to provide a human-like low latency speech.
• Sub-200ms round-trip-time (RTT) thanks hosting Deepgram and open-source LLMs on owned infrastructure.
• One intuitive builder providing full control over agent versioning, testing, and deployment.

The Telnyx difference

Telnyx isn’t just another orchestration layer. It’s the foundation that allows the best AI tools to operate at their full potential without delays, dropouts, or compromises.

Private, global voice network and GPU infrastructure

Unlike cloud-first providers, Telnyx owns and operates a private IP backbone and telephony infrastructure. We route calls through direct PSTN and carrier connections in 40+ countries and anchor media traffic on the edge. Our AI Inference runs on co-located GPUs at these edge locations, so speech data never has to traverse across regions just to get processed. This minimizes hops and slashes latency, making you Voice AI Agents feel fast, fluid, and human.

Unified orchestration layer

Telnyx offers a single platform for telephony, STT, TTS, and LLM orchestration. That means no juggling APIs, coordinating different billing systems, or managing state across tools. You can build, test, and ship Voice AI Agents within one intuitive platform and gain full observability into logs and turn-by-turn interactions.

Native integrations

You can bring your own API key to use GPT-4o, ElevenLabs, and more, or you could use Telnyx-native speech and language models. Test and swap LLMs and TTS voice engines directly within the AI Assistant Builder, and deploy new versions with zero downtime using built-in testing, versioning, and canary deployments.

Telnyx also offers native Model Context Protocol (MCP) support, allowing you to connect your Voice AI Agents to any external API or system. This opens up real-time integrations with popular platforms, such as Zapier, without writing additional code.

Enterprise-grade control and compliance

Telnyx supports regional AI processing, including full support for EU data residency. You can route and anchor voice traffic in the region of your choice and keep model interactions local. All voice, transcript, and metadata are secured on Telnyx infrastructure with unified observability and role-based access controls.

Build with confidence using the best AI tools with Telnyx

The best AI tools are only as good as the system that runs them.

Deepgram, ElevenLabs, and GPT-4o can power amazing experiences, but only if you have the infrastructure to deliver them in real time, globally, and securely.

Telnyx is that infrastructure. We help you combine the world’s best AI tools with the speed, scalability, and simplicity needed for production. Our global voice network, GPU-powered inference stack, and developer-friendly orchestration mean your Voice AI Agents can run at full strength without latency or complexity.