Key Takeaways:
- What are AI voice agents: AI voice agents are AI-powered systems that can hold natural phone conversations and automate tasks like answering and making calls, responding to FAQs, resolving issues, scheduling appointments, qualifying leads, and more.
- What to look for: When evaluating AI voice agents, look for multilingual support, smart interruption handling, seamless hand-offs to human reps, integrations with backend systems, customization options, and analytics tools.
- Top 10 providers in 2025: VoiceSpin, Synthflow, Cognigy, Bland AI, PolyAI, VoiceFlow, Regal, Lindy, Vapi, and Retell AI.
- Why VoiceSpin stands out: VoiceSpin stands out by offering a complete contact center platform with telephony and AI speech analytics.
Imagine a call center rep who handles calls 24/7, speaks fluently multiple languages, never gets tired, and never asks for a coffee break. That’s exactly what an AI voice agent does. While that’s not a real human rep, it can talk to your customers and prospects like a highly knowledgeable person, provide the most accurate information about your products or services, resolve support requests, qualify leads, track orders, schedule appointments – you name it! And, most importantly, it can operate tirelessly around the clock and handle hundreds or even thousands of calls at once.
Now, that’s not a futuristic scenario anymore. Lots of AI voice agent solutions out there can already do all that and much more. But, of course, not all of them are equally advanced. So, how do you choose the best AI voice agent for your business?
No worries – this blog will make it much easier for you. We’ve analyzed the top 10 AI-powered voice agents currently available on the market, compared their core features and capabilities, what makes them unique, and where they lag behind their closest competitors so you can make a well-informed decision quickly. Let’s get started!
What is an AI Voice Agent?
An AI voice agent is an AI-powered software system that can engage users in spoken conversations using Artificial Intelligence technologies like Automatic Speech Recognition (ASR), Natural Language Processing (NLP), and text-to-speech, among others. It can listen, understand spoken language, figure out what you actually mean, and respond with a natural-sounding speech. Here’s what today’s AI voice agents can do:
- Answer inbound calls and manage phone conversations
- Make and handle outbound calls independently
- Pull information from the internal knowledge sources
- Pre-qualify leads and accurately capture lead details
- Automatically make updates in CRMs and databases
- Schedule appointments and perform other actions
- Handle multiple conversations simultaneously
- Interact with customers/ prospects in different languages
- Transfer conversations to human agents with full context
AI voice agents are also known as AI voice bots, AI phone agents, or AI calling bots, to name just a few. In fact, since the technology is still evolving, there’s no single, widely accepted term for these solutions just yet. Nevertheless, the market is literally booming right now as more businesses are looking to automate their customer service and sales operations.
Based on research, the global voice AI agents market size is expected to be worth around USD 47.5 billion by 2034, growing from USD 2.4 billion in 2024.
Key Features to Look for in an AI Voice Agent
Before we jump into the best AI voice agent providers, let’s take a quick look at some of the key features to look for when evaluating different AI voice agent solutions:
Multilingual capabilities
Multilingual AI voice agents can understand and respond to users in multiple languages, similarly to AI chatbots. They can instantly detect the language a person on the other end speaks and switch to that language seamlessly. That can be a game-changer for businesses operating globally.
Smart interruption handling
Smart interruption handling is a critical feature that helps create a more natural experience for users. An AI voice agent should be able to handle interruptions or overlapping speech without breaking the conversation flow. For example, when a user interrupts the AI voice agent mid-response, the system should be able to pause and then adjust the response accordingly based on the user’s question or new input.
Seamless hand-offs to human reps
Even the most advanced AI voice agents aren’t able (yet) to handle complex interactions – and that’s where human reps must step in. When an AI voice agent can’t provide an effective answer or when a user wants to talk to a human rep, the AI agent should be able to smoothly hand off the conversation to a live agent without losing context so the user doesn’t have to start over and repeat the information they already provided earlier.
Integrations with back-end systems
Integrations with CRM systems, helpdesk tools, calendar software, and other back-end systems enable the AI voice agent to update records, look up customer information, trigger automated workflows, and perform specific actions within those integrated systems. For example, if a user wants to reschedule their appointment, the AI voice agent will check the connected calendar for available time slots, suggest alternatives, and update the appointment.
Customization and fine-tuning
Next, you should be able to customize your AI agent’s voice, personality, tone, and overall conversational style to reflect your brand’s identity. That helps you ensure your AI voice agent feels like a natural extension of your organization across all interactions rather than a generic, robotic system.
Analytics and training tools
Finally, when evaluating different AI voice agent providers, make sure that the system includes built-in analytics and training/ coaching tools so you can easily analyze past conversations, identify weak points in your AI agent’s performance, and retrain it to handle similar scenarios with better efficiency.
Top 10 Best AI Voice Agents to Consider in 2025
Now, let’s explore the top 10 AI voice agent providers worth your attention in 2025:
1. VoiceSpin
Unlike other providers listed here, VoiceSpin’s AI voice agent isn’t a standalone solution. VoiceSpin offers a complete AI contact center software platform with VoIP telephony, access to international numbers in 160+ countries, advanced inbound/ outbound call management features, an AI predictive dialer, AI-powered speech analytics, and native integrations with third-party tools (CRM systems, helpdesks, calendar software, and other business apps).
VoiceSpin’s AI voice agent can handle both inbound and outbound calls, run automated workflows, schedule appointments, qualify leads, and perform other actions within integrated systems. Plus, it’s multilingual, it can handle hundreds of calls at once and instantly scale based on your growing needs, and it can hand off conversations to human reps without losing any context.
Key Features:
- Support for 100+ languages and dialects
- RAG-based knowledge retrieval
- Smart interruption handling
- Contextual transition to human agents
- Integrations with third-party systems and APIs
- Advanced reporting and AI speech analytics
Pros
Cons
Best for: Mid-sized to large call centers looking for a scalable solution to automate their customer service and outbound sales operations.
2. Synthflow
Synthflow’s platform is designed for non-technical users – its no-code builder enables businesses to build and deploy AI-powered voice agents pretty quickly and effortlessly. Synchflow’s AI voice agents can answer inbound calls and make outbound calls, schedule appointments, manage orders, qualify leads, update your CRM, and perform many other actions.
With Synthflow, you can either build your AI voice agent from scratch or use ready-made templates. The agent can speak multiple languages, handle dozens or hundreds of simultaneous calls (based on plan), and route complex issues to human reps with full conversation history.
Key features:
- No-code, drag-and-drop agent builder
- RAG-based knowledge retrieval
- Support for 30+ languages and dialects
- Contextual call transfer to human agents
- Native and custom integrations
- Security and compliance features
Pros
Cons
Best for: Small to mid-sized businesses and agencies looking to automate their customer support interactions.
3. Cognigy
Though Cognigy’s platform isn’t voice-first by default, you can use it to deploy AI voice agents through its Voice Gateway module or third-party telephony providers. It is built primarily for large enterprises with high call volumes. While Cognigy’s visual agent builder handles basic flows like FAQs with ease, complex logic or API integrations may need backend skills.
Cognigy’s AI agent can be used in customer service and sales environments as it can handle both inbound and outbound calls. It can speak 100+ languages, handle thousands of concurrent conversations, and transfer calls to live reps along with the context of the conversation.
Key features:
- User-friendly Flow Editor interface
- RAG-based knowledge retrieval
- Support for 100+ languages
- Seamless call routing to human agents
- Integrations with third-party apps
- Reporting and analytics tools
Pros
Cons
Best for: Large enterprises looking to automatically handle their customer service interactions.
4. Bland AI
Bland AI is intentionally built for developers. Though it does offer a drag-and-drop builder, creating complex AI voice agents requires technical knowledge. Bland AI voice agent integrates with various tools to transfer calls to human reps and perform actions like booking meetings, sending SMS texts, or updating CRMs. It’s multilingual, it can automate inbound and outbound calls, and handle thousands of calls at once, making it a great solution for enterprises handling high call volumes.
What’s distinctive about Bland AI is that it offers a wide selection of high-quality, pre-recorded human voices to choose from, while also allowing you to create custom voices in any language, accent, or gender.
Key Features:
- Drag-and-drop agent builder
- Voice API with real-time audio synthesis
- Voice cloning
- Support for multiple languages
- Real-time logs and post-call analysis
- Integrations with third-party apps and APIs
Pros
Cons
Best for: Enterprise-level businesses with large call volumes looking to automate inbound and outbound calls.
5. PolyAI
Poly AI is a conversational AI platform that specializes in AI voice assistants for enterprise customer service. You can use it to build multilingual AI voice agents that can handle FAQs, schedule appointments, collect customer feedback, process payments, and more. The platform is designed to handle large volumes of customer service calls across industries like healthcare, insurance, financial services, retail, telecom, travel, consumer services, and others.
With Poly AI, you can seamlessly transfer calls to your human reps along with all the details of the conversation. With real-time reporting tools, you can instantly see how your AI voice agent is performing and why your customers are calling.
Key Features:
- Support for 45+ languages
- Smart interruption handling
- Natural speech synthesis
- Real-time analytics with custom metrics
- Integrations with third-party apps
- Built-in compliance for regulated industries
Pros
Cons
Best for: Large enterprises looking to build customer service automation.
6. Voiceflow
While Voiceflow is primarily known as a no-code platform for developing chatbot-based conversational AI, it also provides voice functionality through API access and telephony service integrations. It offers a multi-agent workspace, allowing you to build and manage several bots per project, reusable components, multilingual support, scalable knowledge base setup, multi-model support, and BYO (Bring Your Own) LLM capabilities.
The platform can be integrated with 300+ third-party apps to run automated workflows and perform actions. In addition, Voiceflow offers a free plan, so you can get a feel of the platform before committing to a paid subscription.
Key Features:
- Intuitive, easy-to-use flow builder
- Team collaboration tools
- Built-in tools for testing and prototyping
- Custom API integrations
- Private cloud hosting
- Custom LLM support
Pros
Cons
Best for: Small to medium-sized businesses looking to build support and lead gen automation.
7. Regal
Regal offers advanced AI voice agents that can handle both inbound and outbound calls, helping you automate customer service and sales operations. With its no-code voice agent builder, you can easily build, test, and deploy AI voice agents without developer support to automate processes like answering FAQs, resolving basic support requests, scheduling appointments, lead qualification, proactive outreach, sales follow-ups, and reminders.
The agent speaks multiple languages, escalates calls to human agents when needed, and can be customized to align with your brand voice. And the ability to handle high volumes of calls simultaneously makes it a suitable solution for enterprise businesses.
Key Features:
- No-code AI voice agent builder
- Support for 30+ languages
- Customizable voice and agent personality
- A/B testing capabilities
- Seamless escalation to human reps
- 40+ native integrations with third-party tools
Pros
Cons
Best for: Enterprise-grade businesses looking to automate outbound calling campaigns and customer support.
8. Lindy
Lindy is a no-code platform that allows users to build conversational flows without requiring technical expertise. Lindy’s AI voice agent can take and make phone calls for customer support automation, appointment booking, sales outreach campaigns, lead qualification, and survey collection. After the call ends, it automatically logs the conversation, updates your CRM, and sends a summary to the team in Slack.
Lindy’s AI voice agent is multilingual, it can transfer calls to human reps when needed, and can be integrated with a wide range of CRMs and other business apps. And you can get started with a free plan to try the basic features.
Key Features:
- 100+ pre-built templates
- RAG-based knowledge retrieval
- Support for 30+ languages and dialects
- Hand-offs from AI agent to human reps
- Automatic call summaries and reporting
- Integrations with 40+ business apps
Pros
Cons
Best for: Growing businesses who want to start automating early and scale their operations without switching platforms.
9. Vapi
Vapi is a developer-focused platform for building highly customizable voice AI agents that can handle customer support calls, appointment bookings, and outbound sales calls. It’s not beginner-friendly, as it requires coding and API knowledge to build and customize your AI voice agent. On the other side, that’s what sets it apart from similar solutions on the market. Unlike no-code platforms with limited customizations, Vapi offers full developer control and flexibility with an API-first approach.
Beyond that, it supports 100+ languages, offers pre-built templates, and can be scaled to handle thousands of concurrent calls, making it a great solution for handling high call volumes.
Key Features:
- Support for 100+ languages
- Pre-built templates
- A/B testing capabilities
- BYO (Bring Your Own) LLM
- Enterprise-level security features
- Integrations with third-party apps and APIs
Pros
Cons
Best for: Developers, AI consultants, or agencies building white-labeled voice AI solutions for clients.
10. Retell AI
Retell AI lets you build and deploy AI voice agents that can help you automate customer service calls, appointment scheduling, lead qualification, surveys, and debt collection. It is designed primarily for developers. While it provides a basic interface for configuring agents, it does not include a full visual flow builder. Features like drag-and-drop editing, real-time testing, and visual fallback mapping are not available.
Retell AI’s voice agent is multilingual, it can handle interruptions effectively, can transfer calls to human reps with a full conversation context, and provides post-call analytics insights.
Key Features:
- Support for 30+ languages
- Warm call transfer with a hand-off message
- Intelligent interruption handling
- Reporting and analytics
- BYO (Bring Your Own) LLM
- Integrations with CRM, telephony, and business apps
Pros
Cons
Best for: Developer teams and mid-sized to large businesses needing customizable and scalable AI voice agents.
Get Started with VoiceSpin’s AI Voice Agent Now and Automate Your Call Center Operations
AI-powered voice agents are totally transforming the way call centers operate. They can handle inbound and outbound calls independently, maintain super-realistic human-like conversations, deliver round-the-clock support without human intervention, and handle hundreds or even thousands of calls at once – something unheard of a decade ago. And it’s already happening right now.
So, if you’re ready to put an AI voice agent at the forefront of your customer service and sales interactions, VoiceSpin’s solution might just be the right fit for your business. Here’s why:
- Get a full-suite contact center platform with VoIP telephony: With VoiceSpin, you don’t just get an AI voice bot solution – you get a complete contact center platform with built-in VoIP telephony, access to local numbers in 160+ countries, and tools like AI predictive dialing, omnichannel messaging, AI chatbot integration, and more.
- Handle thousands of concurrent calls and scale up instantly: VoiceSpin’s AI voice agent can easily handle hundreds or thousands of simultaneous calls. And you can scale up instantly by adding more server capacity to keep up with increasing call volumes and customer demand.
- Get access to advanced AI-powered speech analytics tools: VoiceSpin’s AI-powered speech analytics tool unlocks access to features like call transcription, AI call summaries, and custom metrics and KPIs so you can easily stay on top of your voice agent performance and identify improvement opportunities.
Book a demo call now to see VoiceSpin’s AI voice agent and other AI contact center solutions in action and find out how they can help you automate your call center operations while also reducing costs for your business.
Frequently Asked Questions
How do AI voice agents work?
First, AI voice agents convert spoken words into text using Automatic Speech Recognition (ASR). Then, they interpret that text through Natural Language Processing (NLP) to understand user intent and generate an appropriate response. AI voice agents rely on Large Language Models (LLMs) and Retrieval-Augmented Generation (RAG) to provide accurate, contextually relevant responses. Finally, text-to-speech (TTS) technology converts the text response back into natural-sounding speech. Besides answering questions, AI voice agents can also take actions like updating CRM records, booking appointments, managing orders, etc.
What are the benefits of AI voice agents?
AI voice agents take routine tasks off the plate (like answering FAQs, qualifying leads, and rescheduling appointments), saving time and reducing the load on human reps while also freeing them up for more complex tasks. They can operate 24/7, ensuring no call goes unanswered no matter when customers or prospects call.
On top of that, they can handle high volumes of calls simultaneously, interact with users in different languages, and even make outbound cold calls, putting outbound calling campaigns on autopilot. That allows businesses to reduce costs and easily scale their call center operations without bringing in more human reps.
What are the top use cases for AI voice agents?
With the ability to handle both inbound and outbound calls independently, AI voice agents can be used in customer service (FAQs, basic troubleshooting) and sales environments (cold calling, lead qualification) across different industries. For example, healthcare providers can use them to automate appointment scheduling. In e-commerce, they can be used for order tracking, product recommendations, and sales support. In banking and finance, AI voice agents can check account balances, process transactions, and pre-screen loan applicants.
Can AI voice agents replace call center staff?
Yes, but not entirely. AI voice agents excel at answering FAQs, collecting information, qualifying leads, and handling simple inquiries like account balances, order status checks, basic troubleshooting, and appointment scheduling. In fact, in these scenarios, AI voice agents are already replacing human call center reps because they can work 24/7 without breaks and handle multiple calls at once. But when it comes to handling requests that require empathy, judgment, and complex problem-solving, human call center agents are still irreplaceable.
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