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Concurrent call limits control the maximum number of simultaneous outbound calls allowed on an account. This limit applies globally across all outbound voice profiles.

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Default limits

New accounts start with a default concurrent call limit that increases based on account verification:
Verification levelConcurrent calls
Initial setup2
Level 2 verification completed10
Custom limit (contact support)10+

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Error handling

When the application attempts to establish a call that exceeds the configured limit, Telnyx returns a SIP 403 error: 
403 User channel limit exceeded D1
This response indicates that the global account concurrent call limit has been reached.

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Implementing retry logic

Implement exponential backoff when handling limit errors: 
on 403 "channel limit exceeded":
    wait 2^attempt seconds (1s, 2s, 4s, ...)
    retry up to max_retries

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Monitoring

Track concurrent call usage to prevent limit errors:

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Via API

Use GET /v2/calls and filter for status: active to get the current concurrent call count.

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Webhook monitoring

Track call lifecycle events using Voice API webhooks:
  • call.initiated - Increment counter
  • call.hangup - Decrement counter
Maintain an in-memory or database counter to track real-time concurrent usage.

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Best practices

  1. Set alerts - Configure monitoring to alert when usage reaches 80% of the limit
  2. Implement queueing - Queue calls when approaching limits rather than failing immediately
  3. Monitor trends - Track peak usage patterns to anticipate when limit increases are needed
  4. Test error handling - Verify the application handles 403 limit errors gracefully

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Requesting limit increases

For concurrent call limits exceeding 10 channels, contact [email protected]. Include the following information in the request:
  • Current concurrent call requirement
  • Expected growth trajectory
  • Use case description (required for limits exceeding 100 channels)