Make outbound sales calls from Google Sheets using a Retell AI voice agent

Description

This n8n workflow automates outbound phone calls to new leads using Retell AI, with built-in timezone detection to ensure you're only calling during business hours.

Use cases include appointment setting, lead qualification, follow-up surveys, payment reminders, and sales outreach—anywhere you need to scale phone conversations without scaling headcount.

Good to know

You'll need a Retell AI phone number and configured voice agent before using this workflow.
Retell AI offers $10 free credit when you sign up (~73 minutes of calls). Create your account here.
The timezone logic covers common country codes (UK, US, EU, Australia, India, UAE, Singapore, Japan). You can extend this in the Code node.

How it works

A new row in Google Sheets triggers the workflow (you can swap this for a webhook, form, or CRM trigger).
The phone number is sanitised—stripping spaces, dashes, and brackets so it's in the correct format for dialling.
The lead's timezone is determined from their country code, and the workflow checks whether it's between 8am-5pm local time. If not, it waits and retries.
Retell AI places the outbound call using your configured voice agent.
The workflow polls Retell's API until the call ends, then retrieves the transcript. You can replace this with a Retell webhook if you'd rather.
The Google Sheet is updated to mark the lead as "Called", as well as entering the call summary, transcript, call sentiment, and other useful details from Retell's call logs.

Requirements

Retell AI account with a phone number and voice agent
Google Sheets with columns: Phone Number, Name, Status

Customising this workflow

Change the trigger**: Replace Google Sheets with a webhook, n8n form, or CRM trigger (HubSpot, Pipedrive, etc.)
Adjust calling hours**: Modify the IF node to change the 8am-5pm window
Expand timezone coverage**: Add more country codes to the mapping in the "Get lead's timezone" Code node
Add your own AI analysis**: We currently use Retell AI's default call summary - but you could add an agent that extracts different insights (e.g., buying signals, objections)
Route the output elsewhere**: Send results to Slack, a CRM, email, or Airtable instead of updating Google Sheets

Built by Marcus Taylor (@intellagents / voiceai.guide)