Make an Outbound Call... does nothing

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The 400 Bad Request error indicates your outbound call request is being rejected due to invalid parameters(1). Here are the most common causes:

Phone Number Configuration Issues

Your phone number must be properly configured before making outbound calls(2). Specifically:

  • The from_number must be a Retell-managed or imported number(2)(1)
  • You need to bind an outbound agent to your phone number(2)
  • The number must be in E.164 format (e.g., +14157774444)(1)(3)

Required Setup Steps

Before making outbound calls, ensure you’ve completed these configurations(2):

  1. Bind an agent to your phone number: Navigate to your phone number settings and assign an outbound agent(2)
  2. Verify number format: The destination number must be in E.164 format with country code, no spaces or special characters(1)(3)
  3. Check international calling: If calling outside the US with a Retell-purchased number, verify the destination country is in the 15 supported countries(2)

Common 400 Error Causes

Based on similar cases, the 400 error typically occurs when(4)(5):

  • The from_number is not a valid Retell phone number(4)
  • No outbound agent is bound to the phone number(2)
  • The phone number format is incorrect (not E.164)(1)(3)
  • The destination country is not supported for your number type(2)

Quick Fix

Check your phone number configuration in the dashboard(2):

  1. Go to “Phone Numbers” tab(6)
  2. Click on your purchased number
  3. Under Outbound Agent, ensure an agent is selected(2)
  4. Verify the number shows as active

If you continue experiencing issues after verifying these settings, check out these resources: