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Improving your connection rate is crucial for campaign success. This guide covers why calls fail, how to configure retries effectively, and how to analyze your results.

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Why calls fail

Understanding failure reasons helps you configure better retries:
OutcomeCauseRetry helps?
BusyRecipient on another callYes, likely
No AnswerRecipient unavailableYes, try different time
RejectedRecipient declined callMaybe, depends on reason
VoicemailMachine answeredDepends on goal
Network ErrorTechnical issueYes, usually temporary

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Measuring your baseline

Before optimizing, measure your current performance: 
curl -X GET /program-executions/EXECUTION_ID \
  -H "x-api-key: YOUR_API_KEY"
Calculate your connection rate: 
Connection Rate = contactsCompleted / totalContacts × 100
Typical benchmarks:
  • First attempt: 20-40% connection rate
  • With 1 retry: 30-50%
  • With 2-3 retries: 40-60%
Your results will vary based on audience, timing, and industry.

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Choosing a retry strategy

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No retries

{ "type": "none" }
Use when:
  • Testing flows
  • One-shot notifications
  • You’ll handle retries externally
  • Very time-sensitive messages

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Fixed delay

{
  "type": "fixed_delay",
  "delayMinutes": 30,
  "maxRetries": 2
}
Use when:
  • Standard campaigns
  • Predictable retry timing needed
  • Consistent recipient behavior expected
Recommended settings:
UrgencyDelayMax RetriesTotal Attempts
High15 min3-44-5
Medium30-60 min2-33-4
Low120+ min1-22-3

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Scheduled

{
  "type": "scheduled",
  "retryDates": [
    "2025-01-20T10:00:00Z",
    "2025-01-20T15:00:00Z",
    "2025-01-21T10:00:00Z"
  ]
}
Use when:
  • Different times of day might work better
  • Compliance requires specific timing
  • Multi-day campaigns
  • Weekend/weekday differences matter

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Optimizing retry timing

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Finding the best times

Track which retry times produce the best results: 
Morning (9-11 AM): Often best for business contacts
Midday (12-2 PM): Lower answer rates (lunch)
Afternoon (2-5 PM): Good for most audiences
Evening (5-8 PM): Best for consumer contacts

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Day of week patterns

  • Monday: Often busy, moderate answer rates
  • Tuesday-Thursday: Generally best days
  • Friday: Lower afternoon rates
  • Weekend: Varies widely by audience

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Spacing your retries

Attempt 1: Campaign start
Attempt 2: +30-60 minutes
Attempt 3: Different time of day
Attempt 4: Next day
This gives you coverage across different availability patterns.

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Combining retries with pause windows

Retries respect pause windows. Configure them together: 
{
  "retryStrategy": {
    "type": "fixed_delay",
    "delayMinutes": 60,
    "maxRetries": 3
  },
  "pauseWindows": {
    "monday": [
      { "startAt": { "hour": 12, "minute": 0 }, "endAt": { "hour": 14, "minute": 0 } },
      { "startAt": { "hour": 18, "minute": 0 }, "endAt": { "hour": 23, "minute": 59 } }
    ]
  }
}
This ensures retries don’t happen during lunch or after hours.

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Analyzing retry results

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Call reports

Get detailed attempt information: 
curl -X GET /call-report/JOB_ID \
  -H "x-api-key: YOUR_API_KEY"
Response shows all attempts: 
{
  "attempts": [
    { "attempt": 1, "outcome": "busy", "call": { "status": "busy" } },
    { "attempt": 2, "outcome": "no_answer", "call": { "status": "no_answer" } },
    { "attempt": 3, "outcome": "completed", "call": { "status": "completed" } }
  ]
}

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Metrics to track

Per-attempt metrics:
  • Connection rate per attempt number
  • Time of day correlation
  • Day of week correlation
  • Outcome distribution
Campaign metrics:
  • Overall connection rate
  • Average attempts needed
  • Retry conversion rate (failed → success)

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Retry conversion analysis

Calculate how effective your retries are: 
Retry Conversion Rate = (Contacts completed after retry) / (Contacts retried) × 100
If your retry conversion rate is low (less than 10%), consider:
  • Different retry timing
  • Fewer retries (save resources)
  • Different audience segmentation

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Handling persistent failures

Some contacts never connect. After exhausting retries:
  1. Export failed contacts
  2. Analyze patterns
    • Same phone number format?
    • Specific regions?
    • Certain times?
  3. Take action
    • Remove invalid numbers
    • Try alternative channels (SMS, email)
    • Flag for manual follow-up

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Identifying patterns

Failed contacts by outcome:
- 60% no_answer → Try evening hours
- 30% busy → More retries might help
- 10% rejected → Likely wrong numbers

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A/B testing retry strategies

Test different strategies to find what works:

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Test setup

  1. Split your audience into test groups
  2. Create separate programs with different strategies
  3. Run simultaneously
  4. Compare results

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Example comparison

Group A: 
{ "type": "fixed_delay", "delayMinutes": 30, "maxRetries": 2 }
Group B: 
{ "type": "fixed_delay", "delayMinutes": 60, "maxRetries": 3 }
Group C: 
{
  "type": "scheduled",
  "retryDates": ["2025-01-20T15:00:00Z", "2025-01-21T10:00:00Z"]
}

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Measuring results

After campaigns complete, compare:
GroupConnection RateAvg AttemptsResource Usage
A45%1.8180 calls
B52%2.4240 calls
C48%2.1210 calls
Choose based on your priorities (connection rate vs. efficiency).

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Advanced techniques

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Progressive retry spacing

Increase delay between attempts: 
{
  "type": "scheduled",
  "retryDates": [
    "2025-01-20T10:30:00Z",
    "2025-01-20T12:00:00Z",
    "2025-01-20T15:00:00Z"
  ]
}
This schedules retries at +30 min, +90 min, and +180 min intervals. Useful when you don’t want to seem aggressive.

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Time-zone aware scheduling

For contacts across time zones:
  1. Segment audience by region
  2. Create separate programs
  3. Schedule based on local time

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Outcome-based routing

Use flow conditions to handle voicemail differently: 
{
  "type": "dial",
  "config": { "enableAMD": true },
  "outputs": {
    "onAnswer": "human-flow",
    "onVoicemail": "leave-message"
  }
}
This routes voicemail to leave a message instead of triggering a retry.

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Best practices summary

  1. Start with moderate retries - 2-3 retries, 30-60 minute delay
  2. Use pause windows - Respect recipient time
  3. Track your metrics - Measure before and after changes
  4. Test different approaches - A/B test strategies
  5. Analyze failures - Understand why contacts don’t connect
  6. Iterate - Continuously improve based on data

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Common mistakes

  • Too many retries - Annoying recipients, wasting resources
  • Retrying too quickly - Situation hasn’t changed
  • Ignoring time zones - Calling at inappropriate hours
  • Not measuring - Can’t improve what you don’t track
  • One strategy for all - Different audiences need different approaches

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Next steps

Retry Strategies

Complete configuration reference.

Pause Windows

Timing controls.

Executions

Monitoring progress.