Handling Failed Calls

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.

Why calls fail

Understanding failure reasons helps you configure better retries:

Outcome	Cause	Retry helps?
Busy	Recipient on another call	Yes, likely
No Answer	Recipient unavailable	Yes, try different time
Rejected	Recipient declined call	Maybe, depends on reason
Voicemail	Machine answered	Depends on goal
Network Error	Technical issue	Yes, usually temporary

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.

Choosing a retry strategy

No retries

{ "type": "none" }

Use when:

Testing flows
One-shot notifications
You’ll handle retries externally
Very time-sensitive messages

Fixed delay

{
  "type": "fixed_delay",
  "delayMinutes": 30,
  "maxRetries": 2
}

Use when:

Standard campaigns
Predictable retry timing needed
Consistent recipient behavior expected

Recommended settings:

Urgency	Delay	Max Retries	Total Attempts
High	15 min	3-4	4-5
Medium	30-60 min	2-3	3-4
Low	120+ min	1-2	2-3

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

Optimizing retry timing

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

Day of week patterns

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

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.

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.

Analyzing retry results

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" } }
  ]
}

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)

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

Handling persistent failures

Some contacts never connect. After exhausting retries:

Export failed contacts
Analyze patterns
- Same phone number format?
- Specific regions?
- Certain times?
Take action
- Remove invalid numbers
- Try alternative channels (SMS, email)
- Flag for manual follow-up

Identifying patterns

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

A/B testing retry strategies

Test different strategies to find what works:

Test setup

Split your audience into test groups
Create separate programs with different strategies
Run simultaneously
Compare results

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"]
}

Measuring results

After campaigns complete, compare:

Group	Connection Rate	Avg Attempts	Resource Usage
A	45%	1.8	180 calls
B	52%	2.4	240 calls
C	48%	2.1	210 calls

Choose based on your priorities (connection rate vs. efficiency).

Advanced techniques

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.

Time-zone aware scheduling

For contacts across time zones:

Segment audience by region
Create separate programs
Schedule based on local time

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.

Best practices summary

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

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

Next steps

Retry Strategies

Complete configuration reference.

Pause Windows

Timing controls.

Executions

Monitoring progress.

Introduction

Getting Started

Core Concepts

Features

Agent Studio

Guides

Handling Failed Calls

Why calls fail

Measuring your baseline

Choosing a retry strategy

No retries

Fixed delay

Scheduled

Optimizing retry timing

Finding the best times

Day of week patterns

Spacing your retries

Combining retries with pause windows

Analyzing retry results

Call reports

Metrics to track

Retry conversion analysis

Handling persistent failures

Identifying patterns

A/B testing retry strategies

Test setup

Example comparison

Measuring results

Advanced techniques

Progressive retry spacing

Time-zone aware scheduling

Outcome-based routing

Best practices summary

Common mistakes

Next steps

Retry Strategies

Pause Windows

Executions

Introduction

Getting Started

Core Concepts

Features

Agent Studio

Guides

Documentation Index

​Why calls fail

​Measuring your baseline

​Choosing a retry strategy

​No retries

​Fixed delay

​Scheduled

​Optimizing retry timing

​Finding the best times

​Day of week patterns

​Spacing your retries

​Combining retries with pause windows

​Analyzing retry results

​Call reports

​Metrics to track

​Retry conversion analysis

​Handling persistent failures

​Identifying patterns

​A/B testing retry strategies

​Test setup

​Example comparison

​Measuring results

​Advanced techniques

​Progressive retry spacing

​Time-zone aware scheduling

​Outcome-based routing

​Best practices summary

​Common mistakes

​Next steps

Retry Strategies

Pause Windows

Executions

Why calls fail

Measuring your baseline

Choosing a retry strategy

No retries

Fixed delay

Scheduled

Optimizing retry timing

Finding the best times

Day of week patterns

Spacing your retries

Combining retries with pause windows

Analyzing retry results

Call reports

Metrics to track

Retry conversion analysis

Handling persistent failures

Identifying patterns

A/B testing retry strategies

Test setup

Example comparison

Measuring results

Advanced techniques

Progressive retry spacing

Time-zone aware scheduling

Outcome-based routing

Best practices summary

Common mistakes

Next steps