AI voice agents have moved far beyond simple call bots. They now handle real conversations, qualify leads, support customers, and even update systems without human input. The best AI voice agent software helps businesses save time, improve efficiency, and deliver consistent service across every call.
Companies use these tools to manage sales calls, route support requests, and provide quick answers without long wait times. Some platforms focus on lifelike voice quality, while others specialize in automation, scalability, or seamless integrations with existing systems.
With options like CallRail, JustCall, Retell AI, Synthflow, and Smith.ai, teams can compare features that match their specific goals. Each tool takes a different approach, from advanced call tracking to full-service automation, making it easier to choose the right fit for growing business needs.
CallRail
CallRail’s Voice Assist uses AI to answer inbound calls, qualify leads, and schedule appointments. It helps businesses capture more opportunities by ensuring that no call goes unanswered, even outside normal hours.
Features & benefits
Voice Assist engages callers in real-time conversations using natural language. It can answer common questions, collect lead details, and handle appointment requests without human involvement. This reduces missed calls and allows staff to focus on higher-value work.
The system integrates with CallRail’s call tracking and conversation intelligence tools, giving businesses a single platform for managing calls and analyzing performance. Automated call summaries and searchable transcripts make reviewing conversations faster and more accurate.
Businesses can also use Voice Assist to improve lead quality. By asking qualifying questions, it identifies serious prospects and routes them appropriately. This process helps reduce wasted time on unqualified leads and supports better sales outcomes.
For a deeper look at how the tool works, the AI voice assistant guide explains common use cases and decision factors.
Audience
Voice Assist is designed for small and mid-sized businesses that rely on phone calls to generate revenue. Service providers such as home services, healthcare, and legal practices often benefit the most since they receive high call volumes and need fast lead response.
Marketing agencies also use the tool to support clients. By combining call tracking with automated call handling, agencies can show clear results while reducing missed opportunities for their clients.
The tool is not limited to one industry. Any business that sees value in capturing every inbound call can apply it. For example, retail shops, professional services, and appointment-driven businesses can all use the system to ensure consistent customer engagement.
CallRail’s Voice Assist rollout highlights how it supports both direct businesses and agencies, making it flexible for different needs.
Pricing
CallRail offers Voice Assist as an add-on to its platform. The cost starts at $95 per month, which includes 50 calls. Only calls over 15 seconds incur a charge. Additional calls are billed at $1 per call, once the 50 calls limit is reached.
This structure makes it predictable for budgeting, especially for businesses with steady call volumes. Companies with higher call traffic can scale usage without committing to larger upfront fees.
When compared to the cost of missed leads, the investment can be reasonable for many businesses. It reduces the need for extra staff while still maintaining coverage 24/7.
More details on cost and value are outlined in the overview on capturing every lead, which explains how the tool helps convert calls into revenue.
In just six weeks, our answered calls increased by 118%. Voice Assist is helping us turn more calls into customers.
Phil Green
Founder, Rapid Repair Pro
JustCall
JustCall combines traditional VoIP features with AI-driven automation. It offers businesses a way to handle inbound and outbound calls more efficiently while reducing missed opportunities and improving response times. The platform integrates voice, SMS, and email into one system, making AI a built-in part of the workflow rather than a separate tool.
Features & benefits
The AI Voice Agent can answer calls, qualify leads, and book appointments without human involvement. It also manages FAQs, routes calls based on set rules, and falls back to a live agent when needed. This reduces repetitive work for staff and ensures customers receive quick responses.
Customization options allow businesses to adjust tone, language, and voice style. The system can pull information from over 300 connected sources, such as knowledge bases and scripts, to provide accurate answers.
Integration is another strength. JustCall connects with Salesforce, HubSpot, Zoho, Google Meet, and Zoom. Data can also move through APIs to call tracking tools, keeping customer records consistent across platforms.
The AI can also send follow-up text messages, schedule surveys, and automate reminders. These features make it useful for both sales and support teams that want to maintain engagement after a call ends.
Audience
JustCall is best suited for mid-sized to large businesses that handle a high volume of calls. Agencies, franchises, and multi-location companies benefit most from its ability to centralize communication across teams.
It works well for industries where after-hours availability is important, such as real estate, healthcare, and service providers. The AI Voice Agent can capture leads or handle support requests even when staff are unavailable.
Companies that want a single platform for calls, texts, and email will find value in the unified setup. Unlike point solutions that only manage one channel, JustCall’s approach helps reduce tool sprawl and simplifies reporting.
Teams that need flexibility in call handling also gain from features like conditional routing and AI fallback. This ensures no call is left unanswered, whether during peak hours or outside business hours.
Pricing
Pricing follows two layers: a user subscription and an AI usage add-on. Core plans start at $29 per user per month, which covers the communication platform itself. The AI Voice Agent is purchased separately.
For predictable costs, businesses can choose fixed packages. The Lite plan is $99 per month for 100 minutes, while the Max plan is $249 per month for 300 minutes. Both include overage charges of $0.99 per minute.
Pay-as-you-go is also available at $0.99 per minute without a minimum. Discounts apply as usage grows, bringing rates closer to $0.79 per minute at 1,000 minutes and as low as $0.50 per minute at very high volumes.
Annual commitments start at $150, covering about 200 minutes. This model gives companies the choice between smaller commitments or scaling up with volume discounts as call traffic increases.
Retell AI
Retell AI is designed for enterprises that need high-performance voice agents at scale. It emphasizes technical precision, offering low-latency conversations, accurate transcription, and seamless API-driven integrations with existing systems.
Features & benefits
Retell AI focuses on conversation quality. Its proprietary turn-taking model predicts when to speak or pause, reducing interruptions and improving flow. This makes calls feel smoother and less robotic.
The platform supports real-time CRM synchronization, database lookups, and outbound call triggers through APIs. Businesses can automate tasks like appointment scheduling, account updates, and lead follow-ups without manual intervention.
For customer service, it includes warm transfer support. If a call needs escalation, the AI passes the full context to a human agent, so the customer does not need to repeat details. Monitoring tools track call quality, sentiment, and task completion.
With the ability to handle 20–30 million calls per month, Retell AI demonstrates its scalability. Enterprises benefit from infrastructure that can manage high call volumes while maintaining consistent performance.
Audience
Retell AI is built for mid-market and enterprise organizations that handle large numbers of phone interactions. Its pricing and technical setup make it less suited for small businesses without dedicated development teams.
The platform appeals to technology-driven companies that want granular control over call flows and integrations. Developers can use APIs and webhooks to connect the system with CRMs, databases, and telephony providers.
Industries such as healthcare, retail, and financial services use Retell AI to automate routine calls while keeping human agents available for complex cases. The platform’s compliance with standards like SOC 2 and HIPAA also makes it practical for regulated industries.
Because of its developer-first design, Retell AI works best for teams that can manage usage-based costs and customize workflows. This makes it a strong fit for enterprises that need both flexibility and scale.
Pricing
Retell AI uses a usage-based model where costs depend on active call minutes. The base fee is $0.07 per minute for voice processing. Additional charges apply for the language model and telephony service chosen.
Example cost per minute:
Voice engine - $0.07
LLM (e.g., GPT-4o) - $0.05
LLM (e.g., GPT-4o mini) - $0.006
Telephony (e.g., Twilio) - $0.015
The first 10 knowledge bases are included, with each extra one costing $8. Pilot packages range from $5,000 to $15,000, depending on volume and setup needs.
This structure gives enterprises flexibility but requires close cost management. Since charges vary by usage, businesses must track call minutes and LLM consumption to forecast expenses accurately.
Synthflow
Synthflow is a voice AI platform designed to automate inbound and outbound calls while keeping setup simple. It focuses on no-code deployment, flexible pricing, and features that help businesses handle high call volumes without extra agent fees.
Features & benefits
Synthflow offers AI voice agents that can manage tasks like lead qualification, appointment scheduling, call routing, and basic customer support. Agents can also confirm details, reschedule bookings, or transfer calls to a human when needed.
The system is prompt-based, so users can control tone, greetings, and behavior without training data. It remembers context during a call and can handle interruptions smoothly, making conversations sound more natural.
Integrations include HubSpot, Salesforce, and GoHighLevel, as well as custom workflows through APIs and webhooks. This allows the AI to check databases in real time, update CRMs, or trigger actions during calls.
Scalability is another strength. Synthflow supports unlimited concurrent calls, ensuring businesses can handle peak traffic without throttling. Built-in analytics track call outcomes, appointment rates, and drop-offs, while APIs enable deeper reporting such as cost per lead or attribution tracking.
Audience
Synthflow is built for agencies and growing businesses that need to manage calls at scale. Marketing and lead generation agencies with dozens of clients can create unlimited AI assistants without extra per-agent costs, making it cost-effective for multi-client setups.
It also fits SMBs and service-based companies that want to automate after-hours calls, appointment booking, or routine support. For teams without technical staff, the no-code design lowers the barrier to adoption.
Larger enterprises benefit from the ability to integrate directly with CRMs or internal systems through APIs. This makes it practical for companies that need to tie call data into broader workflows like lead scoring, customer tracking, or sales attribution.
Pricing
Pricing is based only on minutes used per month, with no seat or agent fees. Every plan includes unlimited AI assistants.
Phone numbers cost about $1.50 per month, and international calling is supported through integrations.
This structure makes costs predictable for agencies running multiple assistants, while high-volume users benefit from lower per-minute rates at the enterprise level.
Plan
Monthly cost
Minutes included
Overage rate
Starter
$29
50
$0.12/min
Agency
$1400
6000
$0.10/min
Enterprise
$2400+
20,000
$0.08/min
Smith.ai
Smith.ai combines AI-driven call handling with human backup support to deliver a reliable receptionist solution. It focuses on efficiency for routine tasks while ensuring that complex or sensitive calls are managed with care.
Features & benefits
Smith.ai offers a hybrid model that blends AI automation with live agent support. The AI can answer calls instantly, route them to the right person, and respond to frequently asked questions. When a call requires more judgment, it escalates to a human agent without disruption.
The system supports lead intake, qualification, appointment scheduling, and payment processing. The ability to securely process payments sets it apart from many competitors. Businesses can also run outreach campaigns that mix AI and human agents for proactive customer engagement.
Customization is a key strength. Each setup is tailored to match a company’s services, FAQs, and workflows. The AI can be built online through a self-serve process or with guided onboarding.
Every call is logged in a dashboard with transcripts, recordings, summaries, and charts that show caller type and outcome. This makes it easy to review performance and spot trends.
Audience
The service is designed for small to medium businesses that receive a steady volume of inbound calls. It works well for companies that want to maintain a professional image without hiring a full in-house receptionist team.
Industries such as law, healthcare, home services, and professional services benefit most. These businesses often need accurate intake, scheduling, and payment handling, which Smith.ai supports directly.
Companies that value quality customer service over the lowest possible cost will see the most value. The hybrid model gives them the reassurance of human support while still keeping costs lower than a fully human-powered receptionist service.
For businesses that run sales or customer follow-up campaigns, the outbound calling feature adds another layer of usefulness. This makes Smith.ai more than just an inbound call solution.
Pricing
Smith.ai’s AI receptionist plans start at $97.50 per month for 30 calls. Extra calls cost $4.25 each. Unlike many services, billing is based on calls rather than minutes or seats, which makes costs easier to predict.
The AI-first plans include human backup at no additional charge. This ensures that unexpected or complex calls are still handled professionally.
For businesses that prefer a fully human receptionist service, pricing begins at $292.50 per month. This option is more expensive but offers a traditional live receptionist experience.
The flexible pricing model allows companies to choose between AI-first, hybrid, or human-only solutions depending on their needs and call volume.
