How Thoughtly powers AI voice scheduling with Calendly’s Scheduling API

Thoughtly builds AI voice agents that handle inbound and outbound calls for businesses. Their platform lets companies deploy voice AI that schedules meetings, qualifies leads, answers questions, and completes workflows over the phone.

To power real-time appointment booking through their AI agents, the Thoughtly team integrated Calendly's new Scheduling API. The partnership enables thousands of businesses to turn phone conversations into confirmed meetings without human intervention, while giving Thoughtly a reliable foundation to scale their voice AI platform.

The challenge

Customer demand for scheduling at scale

When businesses started using Thoughtly's AI voice agents to handle inbound calls, the most frequent request was simple: Can it schedule meetings? Customers needed their voice agents to check availability, capture caller details, and book appointments during the conversation.

Thoughtly's customers were already using Calendly across their organizations. Building a new scheduling system or asking customers to switch tools wasn’t realistic.

“Our clients consistently requested a Calendly integration because it's already embedded in their operational workflows, approved by their IT infrastructure, and trusted by their teams across departments. Rather than asking organizations to adopt additional scheduling tools, we recognized the value of integrating with their existing standard.”

Carlos Parga

Product Manager at Thoughtly

Initially, the Thoughtly team developed a workaround to automate bookings through Calendly’s web interface. It worked, but it was fragile. Any changes on the Calendly side required Thoughtly engineering attention, and form validation errors caused booking failures. Thoughtly’s engineering team found themselves spending hours each week on troubleshooting and maintenance.

More importantly, the workaround created risk for customers. A failed booking meant a lost lead. For businesses routing high-value inbound calls through Thoughtly, that was unacceptable.

The Thoughtly team needed a more powerful Calendly API solution to meet their customers' scheduling use cases. When Calendly invited Thoughtly to become a beta partner for the new Scheduling API, it was a perfect match.

The solution

Reliable, scalable scheduling with Calendly’s Scheduling API

The Thoughtly team used Calendly's new Scheduling API to quickly and easily build a new custom workflow, replacing hundreds of lines of automation code with a clean, reliable connection.

The Scheduling API gives Thoughtly direct access to availability, booking, and invitee management through structured endpoints designed for exactly this use case.

Now, with the Create Event Invitee endpoint, voice agents can:

• Check available time slots

• Ask the caller for their preferred time

• Capture their contact details

• Confirm the booking

… all within a natural conversation.

“The transformation from ‘hoping it works’ to ‘knowing it works’ was fundamental to our market credibility. The API provides structured responses, predictable behavior, and enterprise-grade stability that browser automation simply couldn’t deliver.”

Carlos Parga

Product Manager at Thoughtly

Results

A better customer experience and a more competitive product

Thoughtly's customers now convert more inbound calls to confirmed appointments. Voice agents now handle scheduling in real time, eliminating the drop-off that happens when leads are asked to book separately. One customer reported that their AI voice agent books meetings less than 90 seconds into a call.

Thoughtly's platform reliability has improved significantly. Instead of troubleshooting scheduling issues, the team can focus on building new voice AI features and expanding the platform's capabilities.

The partnership also strengthened Thoughtly's competitive position. When enterprise buyers evaluate voice AI platforms, scheduling is now a solved problem. Thoughtly demonstrates live scheduling during sales calls, and prospects see their own Calendly availability pulled into the conversation in real time.

“Our partnership with Calendly has fundamentally repositioned us in the voice AI market. We hope to now be recognized as the platform with the most robust, enterprise-ready Calendly integration, which has become a cornerstone of our competitive differentiation in enterprise sales conversations.”

Torrey Leonard

CEO at Thoughtly

Looking ahead, Thoughtly plans to extend the integration with additional Calendly API capabilities, including team routing, buffer time management, and multi-event workflows. The goal: Let voice agents handle increasingly complex scheduling scenarios without requiring custom development from customers.