10 Best VoIP and SIP Providers for AI Voice Agents (2026)

An AI voice agent needs a phone line, and that line usually comes from a VoIP or SIP provider. The best VoIP providers for AI voice agents offer SIP trunking, reliable call quality, clear per-minute pricing and documented integrations with AI platforms. Carriers like Twilio and Telnyx connect directly; business phone systems like RingCentral and Dialpad work best when you forward calls to the agent.

If you are choosing a phone system for a small team rather than a carrier for an AI agent, see our guide to VoIP phone systems for small business.

What to Look for in a VoIP Provider for AI Integration

Selecting a business VoIP service provider that harmonizes with AI phone agents requires careful consideration. Not all VoIP systems are created equal when it comes to AI compatibility. Here are key features and benefits to keep in mind:

Key Features to Consider

• AI Compatibility: Ensure the virtual phone system supports integration with AI-driven virtual assistants or chatbots. Look for open APIs and compatibility with popular AI platforms.
• Advanced Call Analytics and Reporting: Robust analytics are crucial for understanding call patterns, customer behavior, and AI agent performance. Features like sentiment analysis and keyword tracking can provide actionable insights.
• CRM Integrations: Seamless integration with CRM systems like Salesforce or HubSpot is essential for creating efficient workflows. AI-powered VoIP systems should automatically log calls, update customer records, and trigger relevant actions.

Benefits of Combining VoIP with AI Phone Agents

• Improved Customer Service Through Real-Time Insights: AI can analyze customer sentiment in real-time, enabling agents to tailor their responses and resolve issues more effectively. This leads to higher customer satisfaction and loyalty.
• Cost Savings by Automating Repetitive Tasks: AI-powered VoIP systems can automate routine tasks like answering FAQs, scheduling appointments, powering AI telemarketing campaigns, and processing orders, freeing up human agents to focus on more complex issues.
• Enhanced Personalization in Customer Interactions: AI can personalize interactions by accessing customer data and providing tailored recommendations, making customers feel valued and understood.

10 Best Voice Over Internet Protocol Companies for Your AI Agents

Integrating AI with the top business phone systems enhances efficiency, security, personalization, and communication quality. For businesses leveraging AI agents, selecting the right VoIP provider is crucial. We'll compare voice over IP providers to help you choose the right one for your business.

1. Telnyx

Telnyx is a carrier with its own private IP network and global numbers, offering SIP trunking and programmable voice. Retell AI connects to Telnyx natively, so you can import Telnyx numbers or point a Telnyx SIP trunk at your agent.

Key Features:

• Elastic SIP trunking on its own carrier network
• Programmable Voice API
• Local, toll-free and international numbers from one account
• Call recording and emergency calling

Pros

• Low published per-minute rates with no platform fee
• Call concurrency included at no extra charge
• Native connection to Retell AI for numbers and SIP trunks

Cons

• Built for developers, so setup needs some technical work
• Rates vary by destination and number type

Pricing Plans

• Outbound local calls: from $0.005 per minute
• Inbound local calls: from $0.0032 per minute
• Phone numbers: from $1 per month
• Full rates at telnyx.com/pricing

Who It’s Best For: Teams running AI agents at volume that want carrier-level control and low per-minute costs.

2. Vonage

Vonage offers business communications and APIs, including a Voice API and SIP trunking. Retell AI integrates with Vonage numbers, so you can add an AI voice agent without changing numbers.

Key Features:

• Voice API for making, receiving and controlling calls
• SIP connections for existing phone systems
• Virtual phone numbers in many countries

Pros

• Pay-per-use pricing billed by the second
• Established global network
• Works with Retell AI through Vonage numbers

Cons

• Rates depend on country and number type, so costs take some modelling
• API products are separate from the Vonage Business phone plans

Pricing Plans

• Pay per use, billed per second; see Vonage voice pricing

Who It’s Best For: Teams already on Vonage that want to add AI voice agents without changing numbers.

3. Twilio

Twilio is an all-in-one communication platform that combines powerful channel APIs with AI and data, so you can serve every customer uniquely. It enables making and receiving phone calls, call routing, and AI IVR systems that support customer self-service. Twilio provides a framework to build and host Assistants for customer-facing use cases.

Key Features:

• Twilio AI Assistants
• Programmable Voice
• Voice Intelligence
• Twilio Flex
• Google Dialogflow CX integration

Pros

• Offers a wide array of communication channels
• Integrates easily with various platforms (SMS, WhatsApp, web chat, mobile)
• Provides tools for building custom AI-powered communication solutions

Cons

• Implementing Twilio's solutions may require more technical expertise compared to some other providers
• Pricing can vary depending on usage and features

Pricing Plans

• Local calls: $0.0140 per minute outbound, $0.0085 per minute inbound
• Toll-free calls: $0.0140 per minute outbound, $0.0220 per minute inbound
• Browser/App Calling: $0.0040 per minute
• SIP Interface: $0.0040 per minute

Who It’s Best For: Businesses of all sizes looking to build highly customizable, AI-powered communication experiences across multiple channels. Particularly well-suited for those who need robust APIs and the flexibility to create tailored solutions.

4. RingCentral

RingCentral is a leading UCaaS (Unified Communications as a Service) provider known for its reliability and extensive feature set, offering robust voice, video, and messaging solutions. It eliminates the need for on-premises PBX hardware.

Key Features: 

• AI-driven transcription, call analysis
• Real-time sentiment analysis
• CRM integrations (Salesforce, etc.)
• Enhanced collaboration capabilities
• Automatic call-back
• Call monitoring
• Voicemail to email
• E911 service
• SIP phone support
• Video conferencing

Pros

• Reliable under high call volumes
• Intuitive user interface
• Strong analytics tools
• Boasts 300+ integrations like Salesforce, Oracle, Dropbox, Zendesk, Google, and Microsoft
• Offers advanced and intelligent call routing features

Cons

• Limited customization options for reports
• UI can be occasionally complex to use, and some features can be overwhelming for new users
• Can be expensive for some businesses as the number of users increases.

Pricing Plans

• Core Plan: $20 per month per user paid annually
• Advanced Plan: $25 per user per month paid annually
• Ultra Plan: $35 per user per month paid annually.

Who It’s Best For: Enterprises needing scalable communication solutions with advanced analytics; also well-suited for small businesses needing a reliable phone system, HD video, and messaging.

5. Dialpad

Dialpad is an intelligent and multi-functional VoIP service known for its AI-powered communication capabilities, integrating SMS, messaging, voice, and video features into a single platform.

Key Features:

• AI-powered call summaries and analytics.
• Voice intelligence
• Real-time transcription
• Voice to actionable summaries using generative AI technology
• AI-powered analytics

Pros

• User-friendly interface
• AI-powered analytics and summaries
• Unlimited calling under all plans
• Regular updates to the tool

Cons

• Video conferencing feature limits participation
• Some user complaints of glitches in the app version
• Analytics report does not include call quality information

Pricing Plans

• From $15 per user per month billed annually (Standard).

Who It’s Best For: Sales and recruiting teams, small to medium-sized businesses looking for an affordable and user-friendly VoIP solution.

6. 8x8

8x8 is a comprehensive VoIP and unified communication provider offering voice, video, messaging, and contact center services.

Key Features:

• Strong security and compliance
• Reliable performance
• Global reach
• AI-powered analytics

Pros

• Robust security features are a plus
• Global reach helps businesses expand
• Unified communication solutions are helpful

Cons

• Can be complex to set up initially
• Less intuitive interface than some competitors

Pricing Plans

• Custom pricing; contact sales.

Who It’s Best For: Small to mid-sized businesses needing a unified communication solution with global reach.

7. Nextiva

Nextiva is a well-renowned name in the list of VoIP providers in the USA. It provides a range of solutions designed for different sizes of companies.

Key Features:

• AI-powered analytics
• CRM integrations
• Call center features

Pros

• Excellent customer support offered
• Offers reliable uptime

Cons

• Pricing can be higher than some competitors

Pricing Plans

• Business phone plans from $15, $25 and $75 per user per month billed annually; contact center plans are priced separately.

Who It’s Best For: Businesses of all sizes needing a reliable VoIP solution with strong customer support.

8. Quo (formerly OpenPhone)

Quo, formerly OpenPhone, is a modern business phone system designed for startups and small businesses. It provides a user-friendly interface and focuses on making business communication simple and efficient.

Key Features:

• Unlimited calls in US/Canada
• SMS/MMS messaging
• Shared phone numbers
• Integrations with CRM and other tool
• Call recording
• Voicemail transcription and snippets
• Sona AI agent on every plan, with about 10 AI-handled calls a month included

Pros

• Affordable, transparent pricing tiers
• Easy setup, intuitive interface

Cons

• Limited advanced call features
• No 24/7 live support

Pricing Plans

• Starter: $15 per user per month billed annually ($19 monthly)
• Business: $23 per user per month billed annually ($33 monthly)
• Scale: $35 per user per month billed annually ($47 monthly)

Who It’s Best For: Small businesses looking for an affordable and easy-to-use VoIP solution.

9. Zoom Phone

Zoom Phone is a cloud-based business phone solution integrated within the Zoom Workplace platform, providing a streamlined unified communications experience.

Key Features:

• Metered or unlimited US/Canada calling
• Team messaging
• Video conferencing
• Direct dial numbers (Global Select plan)
• Call recording
• Optional add-on for international calling.

Pros

• Affordable entry-level plans
• User-friendly and integrates with Zoom Workplace

Cons

• Metered plan charges extra
• Limited advanced features

Pricing Plans

• From $10.50 per user per month (Metered, billed annually).

Who It’s Best For: Businesses already using Zoom Workplace, those needing basic VoIP features, and those seeking affordable options.

10. Aircall

Aircall is a customer communication and VoIP services platform for SMB sales and support teams.

Key Features:

• AI conversational intelligence
• Conversation Center
• Power Dialer
• Analytics
• SMS

Pros

• Utilize AI-driven insights to enhance communication strategies and understand customer sentiments
• Manage all customer interactions across various channels in a unified inbox
• Automate outbound calling processes to boost sales productivity and reach more prospects efficiently

Cons

• Can be more expensive than other options

Pricing Plans

• Essentials: $30 per user per month
• Professional: $50 per user per month
• Custom: Enterprise-tier pricing 

Who It’s Best For: Customer support and sales teams needing a robust call center solution.

Choose a VoIP Partner for Your AI Phone Agents Wisely

Choosing a VoIP provider that integrates seamlessly with AI answering service capabilities is crucial for enhancing communication efficiency and customer satisfaction. AI features help businesses automate routine calls and learn from every conversation. Each provider offers unique strengths tailored to different business requirements.

Before making a decision, carefully evaluate your specific business needs, budget, and technical capabilities. Explore these top providers to transform your business communication today!

If you're looking for the best AI agents, supercharge your call operations with Retell AI's voice agent platform. Build, deploy, and monitor AI voice agents at scale with call transfer, IVR navigation and pay-as-you-go pricing from $0.07 per minute. Retell connects to Twilio, Telnyx, Vonage or any SIP carrier, so you can keep your current numbers.

VoIP for AI voice agents FAQ

Which VoIP provider is best for AI voice agents?

Carriers with SIP trunking and native AI platform integrations, such as Twilio, Telnyx and Vonage, are the most direct option. If you already use a business phone system like RingCentral or Dialpad, you can forward calls to your AI agent instead of switching providers.

Do AI voice agents need SIP trunking?

Not always. You can buy a number directly from an AI voice platform, but SIP trunking lets you keep your existing carrier and numbers and route calls between the AI agent and your team.