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AI Phone Agents: The 5 Most Popular Synthflow Alternatives (2024)
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#1: Setter AI - AI Phone Appointment Setter
Setter AI is a user-friendly platform for creating AI phone appointment setters without any coding or AI knowledge. The software puts high emphasis on usability and speed and does not require the user to touch any code or prompts.
Setter AI is not a general-purpose AI phone caller, but instead focuses on appointment setting as a use-case. While it can still be used for other use-cases (such as cold calls, customer support, etc.) it stands out most for its direct calendar integrations (Calendly, Google Calendar) and Zapier integration. It can be connected to over 6000+ apps (Facebook Lead Ads, Notion, Stripe, …) for a variety of appointment setting use-cases such as quick phone follow-ups on lead form submission for instance. Read more about the importance of cutting lead response time in sales here.
(+) When to choose Setter AI
- You want to use the AI to book appointments directly to your calendar for you.
- You do not want to touch any prompt, do not work with a developer team and/or want to get started quickly.
- You are already using a popular calendar solution (Calendly, Google Calendar) and Zapier.
(-) When to rather not choose Setter AI
- You are looking for a general-purpose AI phone agent solution (beyond appointment setting).
- You want to set up very complex conversations or workflows.
- You want to control technical components such as the LLM, voice synthesis, phone connection, etc..
Key Facts
- Send unlimited calls
- Integrates with Calendly, Google Calendar and 6000+ apps via Zapier
- 3 free credits for trial (1 credit = 1 call minute)
- Pricing starts at 99 USD / month with 200 credits included
- 30 day money-back-guarantee
- Per-minute price decreases with higher volume. Book a demo here.
Call leads in 10 seconds. Never miss an opportunity again.
Setter AI calls up leads in 10 seconds and reduces your lead response time by 99%.
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#2: Bland AI - High-Level Phone Calling Platform
Bland AI is a developer platform and API for creating AI phone agents. Through its high-level API interface it is highly customizable and serves as a general-purpose solution for setting up complex AI phone agents. The company advertises a wide range of use-cases such as customer support, inbound sales and B2B data collection.
Recently the company has received a lot of attention with a viral billboard campaign: Watch it on X. In this demo Bland AI scores with a competitively low latency. Important to keep in mind though is that functionality of the turbo mode presented in the billboard campaign comes with limited capability (no function calls, meaning the AI can e.g. not book appointments, update your CRM, … mid-call). These come with their slightly higher latency base or enhanced mode instead.
(+) When to choose Bland AI
- You want to customize the prompts and train the AI yourself to create complex conversation flows.
- You want access to a high-level API for abstracting away anything related to AI phone agents (phone connector, voice synthesis, text generation, …).
- You want to use their low-latency turbo mode and don’t need function calls from the AI.
(-) When to not choose Bland AI
- You do not want to touch any prompt, do not work with a developer team and/or want to get started quickly.
- You don’t have time to dive into the world of AI phone agents or are not technically savvy.
- You need control over all components related to conversational AI (phone connector, voice synthesis, text generation, …).
Key Facts
- 2 USD worth of free credits for trial
- $499 per month fixed fee
- Additionally $0.09/minute
- Max 1000 calls /day
- Everything above 1000 calls/day needs an enterprise license starting at $50,000.
- Discord community
#3: Vocode - Open Source Option
Vocode is another general AI phone agents platform with a developer-centric focus. As the only tool on this list the code of their product is available open source, so it can be used for free when hosted by yourself. At the same time Vocode offers a paid hosted option too. It comes with a lot of flexibility and a broad API.
(+) When to choose Vocode
- Clear choice when in need of an open source option or self hosting is desired.
- You want to customize and configure deeper levels of the conversational AI (voice synthesis, LLM-streams, …).
- You want to test conversational AI at a low (financial) cost.
(+) When not to choose Vocode
- You do not want to touch any prompt, do not work with a developer team and/or want to get started quickly.
- Using open source software is not a critical requirement of yours.
- You do not want to deal with handling the various aspects of running a conversational AI (voice synthesis, text generation, …)
Key Facts
- Open source code
- Free plan available
- Plan Developer a 25 USD / month, 100 minutes of premium conversation time/month and 3 numbers
- By default inbound only (outbound calls on request)
#4: Retell AI - LLM-Powered Voice AI
Similar to Synthflow AI and Vocode, Retell AI lets you customize certain technical components of the conversational AI (such as your phone provider and the LLM). They offer an API with broad functionality and put high emphasis on low latency. Again, technical knowledge is preferable and working with prompts is required to create AI phone agents with Retell AI.
(+) When to choose Retell AI
- You want to integrate your own LLM-based text generation.
- You need diverse language options beyond English (Japanese, Hindi, Portuguese, …)
- You want to edit prompts yourself.
(+) When not to choose Retell AI
- You do not want to touch any prompt, do not work with a developer team and/or want to get started quickly.
- You don’t have time to dive into the world of AI phone agents or are not technically savvy.
- You want a subscription-based billing model.
Key Facts
- 10 free call minutes for trial
- $0,08 USD - $0,31 USD cents per minute (based on set up)
- Up to 10 concurrent calls (on the non-enterprise plan)
#5: Air AI - Agency SaaS Platform
Air is a SaaS application that offers ready-to-use AI phone agents. Although Air was one of the first to introduce AI phone agents to the market, it has faced significant criticism from customers due to high upfront license fees and a no-refund policy.
Air AI's Trustpilot reviews may indicate some red flags. With only 2 out of 5 stars, users mention a not properly working service, long implementation times. Furthermore Air advertises itself as plug-and-play, however reviews say intensive coding knowledge is required to implement this software.
(+) When to choose Air AI
- You’d prefer to pay a high upfront fee than to pay as you go with other providers
- You are working with an agency that handles the setup and licencing for you
- You are an agency looking to resell an AI phone calling platform to your customers
(-) When to not choose Air AI
- You do not want to pay an upfront fee of $25,000-$100,000
- You don’t want to be locked into a mandatory commitment period with their SaaS platform
- You want to avoid the hassle of coding or integrating APIs
Key Facts
- One of the first AI phone agent applications
- Starting fee of anywhere from $25,000-$100,000 for agency license holders
- Predominantly negative customer feedback
Conclusion
The AI phone agent market offers many choices, each delivering value in different ways. While most people prefer the comprehensive package offered by Setter AI, other platforms like Bland AI, Synthflow AI, Vocode, Retell AI, and Air AI also have appealing features for some buyers.
Setter AI is a user-friendly platform designed specifically for AI phone appointment setting. It requires no coding or AI knowledge, emphasizing usability and speed. Key features include:
- Direct Calendar Integrations: Connects seamlessly with Calendly and Google Calendar.
- Zapier Integration: Compatible with over 6000 apps for various appointment-setting use cases.
- Unlimited Calls: Make as many calls as needed.
- Trial Credits: 3 free credits to get started (1 credit = 1 call minute).
- Flexible Pricing: Starts at $99/month with 200 credits included, and per-minute prices decrease with higher volumes.
- Money-Back Guarantee: 30-day money-back guarantee if not satisfied.
Choose Setter AI if you want an AI to book appointments directly to your calendar without touching any code or prompts.
Call leads in 10 seconds. Never miss an opportunity again.
Setter AI calls up leads in 10 seconds and reduces your lead response time by 99%.
