Auto Retry on Busy

Auto retry automatically redials a phone number when the initial call attempt fails due to a busy signal, no answer, or network failure. This is essential for outbound campaigns and callback scenarios where reaching the customer is critical.

How Auto Retry Works

Call attempt 1 → Customer busy / no answer
        |
        v
Wait (retry interval, e.g., 30 minutes)
        |
        v
Call attempt 2 → Customer busy / no answer
        |
        v
Wait (retry interval)
        |
        v
Call attempt 3 → Customer answers → Connected
        (or max attempts reached → Mark as unreachable)

Retry Triggers

Auto retry activates based on the call outcome:

Outcome	Should Retry?	Reason
Busy	Yes	Customer is on another call; they may be free later
No answer	Yes	Customer may have been away from the phone
Failed	Yes (once)	Network issue may be temporary
Completed	No	Call was successful
Canceled	No	Call was canceled by the system or user
Invalid number	No	Number does not exist; retry will not help
DND	No	Number is on the Do Not Disturb registry

Configuring Auto Retry

For Outbound Campaigns

When setting up a campaign via the dashboard or Campaigns API, configure the retry settings:

Setting	Description	Recommended Value
Max retry attempts	Maximum number of additional attempts after the first	2-3
Retry interval	Time between retry attempts	30-60 minutes
Retry on busy	Retry when the line is busy	Yes
Retry on no answer	Retry when no one answers	Yes
Retry on failed	Retry on network/connection failure	Yes (1 attempt)
Retry time window	Restrict retries to certain hours	9 AM - 9 PM
Total attempts	First attempt + retries	3-4 total

Via Dashboard

1. Go to Campaigns > Create Campaign (or edit existing).
2. In the Retry Settings section:
   • Enable Auto Retry.
   • Set Max Retry Attempts (e.g., 2).
   • Set Retry Interval (e.g., 60 minutes).
   • Select which outcomes trigger a retry.
3. Save.

Via API

curl -X POST 'https://<api_key>:<api_token>@api.exotel.com/v1/Accounts/<account_sid>/Campaigns' \
  -H 'Content-Type: application/json' \
  -d '{
    "name": "Payment_Reminders",
    "caller_id": "<exophone>",
    "call_flow_id": "<flow_id>",
    "numbers": ["+919876543210", "+919876543211"],
    "retry": {
      "max_attempts": 3,
      "interval_minutes": 60,
      "retry_on": ["busy", "no-answer", "failed"]
    },
    "schedule": {
      "daily_start": "09:00",
      "daily_end": "21:00"
    }
  }'

For Individual API Calls

When using the Connect Two Numbers API or Connect to Flow API, implement retry logic in your application:

import time
import requests

def call_with_retry(customer_number, max_retries=3, interval_seconds=1800):
    for attempt in range(1, max_retries + 1):
        response = exotel_api.connect_call(
            from_number=agent_number,
            to_number=customer_number,
            caller_id=exophone
        )

        call_sid = response['Call']['Sid']

        # Wait for call to complete
        call_status = wait_for_completion(call_sid)

        if call_status in ['completed', 'in-progress']:
            print(f"Call connected on attempt {attempt}")
            return call_sid

        if call_status in ['busy', 'no-answer']:
            if attempt < max_retries:
                print(f"Attempt {attempt} failed ({call_status}). Retrying in {interval_seconds}s...")
                time.sleep(interval_seconds)
            else:
                print(f"All {max_retries} attempts exhausted. Customer unreachable.")
                return None

        if call_status == 'failed':
            # Only retry once for failures
            if attempt == 1:
                time.sleep(60)
                continue
            return None

    return None

Using Status Callbacks for Retry Triggers

Instead of polling for call status, use Status Callbacks to trigger retries:

# Your webhook endpoint
def handle_call_callback(request):
    call_sid = request.POST['CallSid']
    status = request.POST['Status']
    customer_number = request.POST['To']

    if status in ['busy', 'no-answer']:
        # Check retry count
        retry_count = db.get_retry_count(customer_number)

        if retry_count < MAX_RETRIES:
            # Schedule retry
            scheduler.schedule(
                func=make_call,
                args=[customer_number],
                delay=timedelta(minutes=60)
            )
            db.increment_retry_count(customer_number)
        else:
            db.mark_as_unreachable(customer_number)

    elif status == 'completed':
        db.mark_as_contacted(customer_number)

    return Response(status=200)

Retry Interval Strategies

Strategy	Interval Pattern	Best For
Fixed interval	60 min, 60 min, 60 min	Simple, predictable
Increasing interval	30 min, 60 min, 120 min	Avoids annoyance from frequent retries
Time-of-day based	Retry at 10 AM, 2 PM, 5 PM	Targets different parts of the day
Smart interval	Based on past answer patterns	Data-driven, highest connection rate

Fixed Interval

Retries happen at consistent intervals:

Attempt 1: 10:00 AM → No answer
Attempt 2: 11:00 AM → Busy
Attempt 3: 12:00 PM → Connected

Increasing Interval (Exponential Backoff)

Each retry waits longer than the previous:

Attempt 1: 10:00 AM → No answer
Attempt 2: 10:30 AM → No answer (30 min later)
Attempt 3: 11:30 AM → No answer (60 min later)
Attempt 4: 1:30 PM → Connected (120 min later)

This reduces the risk of annoying customers with frequent calls.

Time-of-Day Based

Retry at specific times known for higher answer rates:

Attempt 1: 10:00 AM → No answer
Attempt 2: 2:00 PM → Busy
Attempt 3: 5:00 PM → Connected

tip

Data from most outbound campaigns shows that answer rates are highest between 10-11 AM and 4-6 PM on weekdays. Schedule your retries to target these windows.

Retry Limits and Safety

Maximum Attempts

Context	Recommended Max	Reason
Payment reminders	3-4 attempts	Important but not urgent
Delivery confirmations	2-3 attempts	Time-sensitive
Sales outreach	2-3 attempts	Avoid appearing aggressive
Appointment reminders	2 attempts	Single reminder is usually sufficient
Emergency notifications	5-6 attempts	Critical to reach the person

Regulatory Limits

Regulation	Limit
TRAI (India)	Maximum calls during 9 AM - 9 PM only
General best practice	No more than 3-5 call attempts per number per day
DND compliance	Do not retry DND-registered numbers

warning

Excessive retries can lead to complaints and your ExoPhone being flagged as spam. Limit total attempts to 3-4 per number per day, and always respect the customer's right to opt out.

Monitoring Retry Performance

Track these metrics to optimize your retry strategy:

Metric	Description	Target
First-attempt connection rate	Calls connected on the first try	Above 40%
Retry connection rate	Calls connected on retry attempts	Above 30% per retry
Total connection rate	Calls connected across all attempts	Above 70%
Average attempts to connect	Mean number of attempts before connection	Under 2
Unreachable rate	Numbers that could not be reached after all retries	Under 20%
Retry ROI	Additional connections gained from retries	Positive (each retry should add >10% connections)

Diminishing Returns

Track whether additional retries are worth the cost:

Attempt	Connection Rate (Cumulative)	Incremental Gain
1st attempt	40%	--
2nd attempt	60%	+20%
3rd attempt	70%	+10%
4th attempt	73%	+3%
5th attempt	74%	+1%

In this example, the 4th and 5th attempts yield diminishing returns and may not justify the cost and annoyance.

Best Practices

• Start with 2-3 retries -- This reaches most available customers without excessive attempts.
• Use increasing intervals -- Give customers time between attempts.
• Vary the time of day -- If the first attempt was morning, retry in the afternoon.
• Respect opt-outs -- If a customer indicates they do not want to be called, stop retrying immediately.
• Monitor connection rates per retry -- If the 3rd retry adds less than 5% connections, it may not be worth the cost.
• Combine with SMS -- After 1-2 failed call attempts, send an SMS asking the customer to call back at their convenience.
• Filter invalid numbers -- Do not retry numbers that are invalid, disconnected, or on DND.

Troubleshooting

Issue	Cause	Solution
Retries not happening	Auto retry not enabled	Enable in campaign settings
Too many retries	Max attempts set too high	Reduce to 2-3
Retries at wrong times	Retry window not configured	Set daily start/end times
Same number retried after connection	Status not updated correctly	Check status callback handling
Retries flooding agents	Too many concurrent retries	Limit concurrency in campaign settings

Related

• Outbound Dialer
• Outgoing Calls
• Automated Calls
• Call Analytics
• Campaigns API