Lesson 18: Inbound & Outbound Calls

Retell University Module 5: Deploy & Integrate
1

Inbound & Outbound Calls

Inbound Calls

  • Assign an agent to a phone number
  • When someone calls that number, the agent picks up
  • Configure greeting behavior (immediate vs. dynamic opening)
  • Set business hours and after-hours handling

Outbound Calls

  • Trigger calls via the API
  • Specify: phone number to call, agent to use, dynamic variables
  • Use cases: appointment reminders, follow-ups, outreach campaigns

Batch Calls

  • Make many outbound calls at once
  • Upload a list of phone numbers with variables
  • Set concurrency limits (how many simultaneous calls)
  • Monitor progress and results in real-time
  • Great for campaigns, surveys, and mass notifications

API Example (Outbound Call)

POST /v2/create-phone-call
{
  "from_number": "+14155551234",
  "to_number": "+14155555678",
  "agent_id": "agent_xxx",
  "retell_llm_dynamic_variables": {
    "customer_name": "John Smith",
    "appointment_date": "June 15"
  }
}

KYC Verification

  • Required for outbound calling
  • Verify your identity and business
  • Prevents spam and ensures compliance with TCPA regulations