### Answer Based on conversations in the Retell AI community, users building call center SaaS solutions primarily use Make.com (formerly Integromat) and webhooks to handle email and calendar integrations after calls [(1) ]() [(2) ]() . Common Integration Approaches: 1. Make.com for Workflow Automation Users leverage Make.com to create multi-step workflows that trigger after a call completes . The typical flow involves: - Retell AI sends call completion data via webhook to Make.com [(1) ]() - Make.com processes the data and triggers actions like sending emails or creating calendar appointments - Make.com connects to calendar systems (like GoHighLevel calendars) to book appointments based on call outcomes [(1) ]() [(2) ]() 2. Webhooks for Real-Time Actions Webhooks enable your AI voice agent to trigger actions across systems when specific events happen during or after a call [(3) ]() . When a call ends or an intent is detected, Retell can send JSON-formatted data to your webhook endpoint, which then initiates email sends or calendar bookings [(3) ]() [(4) ]() . 3. Custom Functions During Calls For real-time interactions during the call itself, users implement custom functions that can call external APIs mid-conversation [(5) ]() . This allows the agent to check calendar availability or send confirmation emails while still on the call w

ith the customer . Architecture Example from Community: One user described this flow for GoHighLevel integration: - GHL → Make.com (webhook) [(1) ]() - Make.com pulls calendar availability and starts the Retell call with injected variables - Retell confirms time with the lead and sends booking details back to Make.com - Make.com creates the appointment in the calendar system - Calendar system sends the invite and confirmations The key principle: the system that fetches availability or handles the integration should either start the call or receive webhook data from Retell to ensure proper data flow .

​ To learn more, see the sources I considered: [[1] GHL + Make + Retell](https://community.retellai.com/t/ghl-make-retell/806) [[2] Help need for Integration with Gohighlevel and Outbound Call initiate.](https://discord.com/channels/1186424376300679209/1321436387655815221) [[3] Webhook](https://www.retellai.com/glossary/webhook) [[4] AI Call Platform That Goes Beyond Calling | Retell AI | Retell AI](https://www.retellai.com/blog/ai-call-platform-features-beyond-calling) [[5] Calling Webhooks In The Middle of A Call](https://discord.com/channels/1186424376300679209/1376986877927886979) ​

Feel free to tag @AI Evy with additional questions. I also appreciate feedback, it helps me improve.