From previous guides, you already have numbers purchased or imported. This guide will walk through how to assign agents, and make phone calls.

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Bind Voice Agents

  • Only when you bind agents to a number will the number be able to receive and make calls.
  • You can assign different inbound and outbound agent to the number.
  • You can leave agent unset to disable inbound / outbound (for example, you are doing outbound and don’t want callbacks, you can leave inbound_agent_id unset)
After binding an agent for inbound, you should be able to receive inbound calls already.

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Make Outbound Call

If you are using a number purchased from Retell, right now it’s not able to make international calls. This restriction does not apply to imported numbers, as you have to set geo location permissions yourself at your telephony provider.
Check out Create Phone Call API Reference for all the parameters you can use.
  • from_number is the e.164 string format of the number you purchased earlier.
  • to_number is the phone number you want to call in e.164 string format.
const registerCallResponse = await retell.call.createPhoneCall({
  from_number: '+14157774444', // replace with the number you purchased
  to_number: '+12137774445',  // replace with the number you want to call
  retell_llm_dynamic_variables: { // replace with the dynamic variables you want to send (optional)
    name: 'John Doe',
    blood_group: 'B+'
  },  
  custom_sip_headers: { // replace with custom sip headers you want to send (optional)
    X-Custom-Header: 'Custom Value'
  }
});
console.log(registerCallResponse);

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Understanding CPS (Calls Per Second)

CPS refers to the number of outbound calls that can be initiated per second. This is an important metric to consider when planning your outbound calling strategy:
  • Default CPS Limit: Each account has a default CPS limit of 1 call per second to ensure system stability and prevent abuse.
  • Scaling Considerations: If you’re planning to make a large volume of calls, be mindful of your CPS limit.
  • Throttling: Exceeding your CPS limit may result in call requests being throttled or rejected.
  • CPS Increase: For higher volume needs, contact support to discuss increasing your CPS limit based on your use case.
Best practice is to implement retry logic with exponential backoff in your application when making outbound calls at scale to handle any throttling gracefully.

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Get Call Detail

  • API: You can use Get Call API to get information like transcript, recording, latency tracking, etc.
  • Webhook: You can also setup webhooks to receive real time updates when call is initiated, ends, and analyzed. Read more at Call Webhook Guide.
Triggering Outbound Calls (Using Make.com) See community templates in docs