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Calling guardrails let you restrict when your agent makes outbound calls. Calls outside the allowed window are automatically rescheduled.
Call Tab with Plivo telephony provider, Noise Cancellation, Voicemail Detection, Keypad Input DTMF, Auto Reschedule toggles, and Outbound call timing restrictions toggled on with 9 AM to 9 PM window

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How It Works

1

Enable Restrictions

Toggle on Outbound call timing restrictions in the Call Tab. It is off by default.
2

Set the Allowed Time Window

Pick a start and end time (e.g., 9:00 AM to 9:00 PM).
3

Calls Are Validated Automatically

When a call is triggered, the system checks the current time in the recipient’s local timezone (detected from their phone number).
4

Within Window: Call Goes Through

If the time falls inside the allowed window, the call is made immediately.
5

Outside Window: Call Is Rescheduled

If the time falls outside the window, the call status is set to rescheduled and it is automatically queued for the next allowed start time.
The time window is based on the recipient’s timezone, not yours. A 9 AM start means 9 AM where the recipient is located.

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Configure via API

You can also set calling guardrails through the API when creating or updating an agent. Use call_start_hour and call_end_hour in 24-hour format.
FieldTypeDescription
call_start_hourinteger (0-23)Start of the allowed calling window
call_end_hourinteger (0-23)End of the allowed calling window
curl --request POST \
  --url https://api.bolna.ai/v2/agent \
  --header 'Authorization: Bearer YOUR_API_TOKEN' \
  --header 'Content-Type: application/json' \
  --data '{
    "agent_config": {
      "agent_name": "Sales Agent",
      "agent_welcome_message": "Hello, how can I help you?",
      "calling_guardrails": {
        "call_start_hour": 9,
        "call_end_hour": 21
      },
      "tasks": [...]
    },
    "agent_prompts": {...}
  }'
Hours use 24-hour format: 0 = midnight, 9 = 9 AM, 17 = 5 PM, 21 = 9 PM. call_end_hour must be greater than or equal to call_start_hour.

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Bypass Guardrails for Urgent Calls

Use the bypass_call_guardrails flag to skip time validation for a specific call. When set to true, the call goes through immediately regardless of the configured window. 
curl --request POST \
  --url https://api.bolna.ai/call \
  --header 'Authorization: Bearer YOUR_API_TOKEN' \
  --header 'Content-Type: application/json' \
  --data '{
    "agent_id": "3c90c3cc-0d44-4b50-8888-8dd25736052a",
    "recipient_phone_number": "+14155551234",
    "bypass_call_guardrails": true,
    "user_data": {...}
  }'

Emergency Notifications

Time-sensitive alerts that cannot wait

VIP / Priority Calls

High-priority calls that need immediate delivery
Use the bypass flag responsibly. Calling outside allowed hours may violate local regulations or disturb recipients.

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Common Use Cases

Restrict calls to standard business hours so your agent only reaches out during the workday.
{
  "calling_guardrails": {
    "call_start_hour": 9,
    "call_end_hour": 17
  }
}
Calls triggered outside this window are automatically rescheduled to 9 AM the next day in the recipient’s timezone.
Sales teams often reach prospects in the evening. Extend the window while still avoiding late-night calls.
{
  "calling_guardrails": {
    "call_start_hour": 9,
    "call_end_hour": 21
  }
}
During development, use the bypass flag to test call flows at any time without waiting for the allowed window.
{
  "bypass_call_guardrails": true
}

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In-Call Reschedule Validation

When a recipient asks to reschedule during a call (e.g., “call me back at 10 PM”), the system validates the requested time against the allowed window before scheduling it. Validation priority:
PrioritySourceDescription
1Calling guardrails configcall_start_hour / call_end_hour always takes precedence
2Agent promptIf no guardrails are set, the LLM reads time restrictions from the system prompt
3Default windowFalls back to 9 AM to 9 PM if neither is configured
If the requested time falls outside the allowed window, the reschedule request is rejected entirely. The system does not adjust it to the nearest boundary.
Keep your agent prompt and guardrails config consistent. If the prompt says “call between 10 AM and 6 PM” but guardrails are set to 9 AM to 9 PM, the stricter guardrails config takes priority.

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Calling Regulations to Know

Many countries enforce strict rules on when businesses can make outbound calls. Calling guardrails help you stay compliant.
RegionRegulationAllowed Hours
IndiaTRAI (Telecom Regulatory Authority of India)9:00 AM to 9:00 PM IST. No calls on national Do Not Disturb (DND) registered numbers without consent.
United StatesTCPA (Telephone Consumer Protection Act)8:00 AM to 9:00 PM in the recipient’s local time. Prior express consent required for automated calls.
European UnionePrivacy DirectiveVaries by member state. Most restrict unsolicited calls to business hours and require prior consent.
This is a general reference, not legal advice. Always verify the specific regulations that apply to your use case and region before making outbound calls.

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Next Steps

Call Tab

Configure telephony, noise, and call settings

Batch Calling

Schedule calls in bulk with CSV uploads

Auto Retry

Automatically retry unanswered calls

Make Calls API

Full API reference for the call endpoint