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Not every call connects on the first try. Retry strategies tell Gomobile how to handle failed calls—whether to try again, when, and how many times.

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Why retries matter

Phone calls fail for many reasons:
  • Busy signal
  • No answer
  • Network issues
  • Voicemail (when you need a human)
  • Temporary phone problems
Without retries, these contacts are lost. With smart retries, you can significantly improve your connection rate.

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Strategy types

Gomobile supports three retry strategies:
StrategyBest for
noneOne-shot notifications, testing
fixed_delayMost campaigns, predictable timing
scheduledSpecific time windows, compliance requirements

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No retries

The simplest option—each contact gets one call attempt: 
{
  "retryStrategy": {
    "type": "none"
  }
}
Use this when:
  • You’re testing a flow
  • The message isn’t time-sensitive
  • You’ll handle retries externally
  • One attempt is all you need

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Fixed delay retries

Retry failed calls after a consistent delay: 
{
  "retryStrategy": {
    "type": "fixed_delay",
    "delayMinutes": 30,
    "maxRetries": 3
  }
}
How it works:
  1. First attempt fails
  2. Wait 30 minutes
  3. Second attempt (retry 1)
  4. If that fails, wait another 30 minutes
  5. Third attempt (retry 2)
  6. If that fails, wait 30 minutes
  7. Fourth attempt (retry 3)
  8. If that fails, contact marked as failed
With maxRetries: 3, a contact gets up to 4 total attempts.
Choosing delay times:
DelayUse case
5-15 minUrgent messages, short campaigns
30-60 minStandard campaigns
120+ minLess urgent, spread throughout day

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Scheduled retries

Retry at specific times: 
{
  "retryStrategy": {
    "type": "scheduled",
    "retryDates": [
      "2025-01-20T14:00:00Z",
      "2025-01-21T10:00:00Z",
      "2025-01-22T16:00:00Z"
    ]
  }
}
How it works:
  1. First attempt (at program start time) fails
  2. Next attempt at 2025-01-20T14:00:00Z
  3. If that fails, next attempt at 2025-01-21T10:00:00Z
  4. If that fails, next attempt at 2025-01-22T16:00:00Z
  5. If that fails, contact marked as failed
The number of dates equals the number of retry attempts. When to use scheduled retries:
  • Different times of day might work better
  • Spreading attempts across multiple days
  • Compliance requirements (max calls per day)
  • Specific business hours

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What triggers a retry?

Retries happen when a call fails to connect meaningfully. This includes:
OutcomeTriggers retry?
BusyYes
No answerYes
Voicemail (with AMD)Configurable
RejectedYes
Network errorYes
Human answered, flow completedNo
Human answered, flow errorDepends on error
Successful calls (human answered and flow completed) don’t retry.

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Retry behavior with pause windows

Retries respect pause windows. If a retry is scheduled during a pause window:
  1. The retry waits until the pause window ends
  2. Then it proceeds with the call
This ensures you don’t accidentally call during inappropriate times.

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Monitoring retry progress

Track retries through the execution counters: 
{
  "totalContacts": 1000,
  "contactsCompleted": 650,
  "contactsFailed": 50,
  "contactsPending": 280,
  "contactsInProgress": 20
}
contactsPending includes contacts waiting for retry. As retries process, they move to completed or failed.

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Call reports and retries

The call report API shows all attempts for a contact: 
{
  "jobId": "job-uuid",
  "status": "completed",
  "finalOutcome": "completed",
  "attempts": [
    {
      "attempt": 1,
      "call": { "status": "busy" },
      "outcome": "busy"
    },
    {
      "attempt": 2,
      "call": { "status": "completed" },
      "outcome": "completed"
    }
  ]
}
This helps you understand:
  • How many attempts were needed
  • What outcomes occurred
  • Time between attempts

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Strategy recommendations

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Standard campaigns

{
  "type": "fixed_delay",
  "delayMinutes": 60,
  "maxRetries": 2
}
Three total attempts, one hour apart. Balances persistence with respect.

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Urgent notifications

{
  "type": "fixed_delay",
  "delayMinutes": 15,
  "maxRetries": 4
}
Five total attempts, 15 minutes apart. More aggressive for time-sensitive messages.

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Multi-day campaigns

{
  "type": "scheduled",
  "retryDates": [
    "2025-01-20T10:00:00Z",
    "2025-01-20T15:00:00Z",
    "2025-01-21T10:00:00Z",
    "2025-01-21T15:00:00Z"
  ]
}
Morning and afternoon attempts over two days.

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One-shot with external handling

{
  "type": "none"
}
No retries. Export failed contacts and handle them through another process.

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Best practices

  1. Start conservative - 2-3 retries is usually enough
  2. Space them out - Avoid overwhelming recipients
  3. Respect time zones - Schedule retries during reasonable hours
  4. Monitor results - Track if retries actually help
  5. Consider the message - Urgent = more retries, routine = fewer
  6. Use pause windows - Combine with retries for best results

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Common mistakes

  • Too many retries - Annoying and may get numbers flagged
  • Too short delays - Recipient situation won’t change in 5 minutes
  • Ignoring time zones - Retries at 3 AM don’t help
  • No pause windows - Retrying during lunch hours

Programs

Setting retry strategies.

Executions

Monitoring retry progress.

Pause Windows

Controlling when retries happen.