### Answer You can send an SMS with appointment details during a voice call using SMS nodes built directly into the Retell agent builder. [(1) ]() How to set it up: 1. Open the Retell Agent Builder 2. Insert a Send SMS node into your conversation flow 3. Customize the message and include dynamic variables like

{{first_name}}

or

{{booking_time}}

to personalize the appointment details 4. Place the SMS node to trigger right after your appointment booking function completes SMS flows are deployed using the same phone number infrastructure as voice agents—no extra setup required. Example use case: When confirming an appointment or finalizing a transaction, the agent sends a booking confirmation, calendar invite, or payment link without leaving the call flow. Alternative approach using webhooks/n8n: You can also use a tool call to push the phone number and SMS contents via a webhook, which triggers a Twilio node to send the SMS. [(2) ]() An easier route can be to set up a custom function (Retell supports POST requests directly inside agent config) to handle the SMS sending.

​ To learn more, see the sources I considered: [[1] Unlock AI Texting, SMS, & Chatbots with Retell AI Agents | Retell AI | Retell AI](https://www.retellai.com/blog/unlock-ai-texting-with-retell-ai-voice-agents) [[2] Discord message from @conect242004 on 2025-06-11](https://discord.com/channels/1186424376300679209/1294891368505937952/1382375333344317490) ​

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