Toll-free throughput reference

Technical reference for toll-free number throughput limits, carrier constraints, and message handling behavior.

Quick reference

Toll-free characteristics

Toll-free numbers (800, 888, 877, and similar prefixes) are optimized for inbound customer communication and are rate-limited differently than 10DLC numbers. Because toll-free is designed for two-way customer communication rather than bulk outbound campaigns, carriers impose stricter throughput limits.

Key differences from 10DLC:

• Lower throughput for bulk outbound messaging
• Inbound-focused (you pay for inbound customer calls and SMS)
• Rate limiting emphasizes customer service over marketing volume
• Carrier limits vary significantly by MNO

Carrier throughput limits

Each major US carrier has different rate limiting and message handling for toll-free numbers:

Important: These are typical rates and may vary based on:

• Campaign use case and type
• Historical traffic patterns
• Geographic distribution
• Message content and keywords

Message queuing and throttling

When toll-free numbers approach carrier rate limits, messages are queued and delivered over time:

How queuing works:

1. Your application sends messages faster than carrier rate limit
2. Infobip queues excess messages in order
3. Messages are delivered as rate limit allows
4. Delivery may be delayed 1 to 30 seconds per message

Impact on bulk messaging:

• If you send 1,000 messages through a 5 messages per second toll-free number:
  • Messages take approximately 200 seconds (3.3 minutes) to deliver
  • All messages are eventually delivered, but not immediately
  • Useful for notifications and customer service, not time-sensitive campaigns

Use cases and throughput planning

Appropriate toll-free use cases [#appropriate-toll-free-use-cases-use-cases-and-throughput-planning]

These use cases align with toll-free throughput expectations:

When NOT to use toll-free [#when-not-to-use-toll-free-use-cases-and-throughput-planning]

If you need any of these, consider short code instead:

• High-volume marketing campaigns (>1,000 messages to deliver within minutes)
• Time-sensitive messaging (flash sales requiring immediate delivery)
• Rapid sequential messaging to many recipients
• Guaranteed delivery throughput (toll-free varies by carrier)

Checking toll-free campaign throughput

Through web interface [#through-web-interface-checking-toll-free-campaign-throughput]

Infobip does not display specific throughput limits in the web interface. Carrier-specific limits are determined during campaign registration and optimization.

Through API [#through-api-checking-toll-free-campaign-throughput]

To understand your toll-free campaign's expected behavior:

1. Check campaign status: Registered status indicates active on carriers
2. Monitor delivery metrics: Track actual throughput in reports
3. Contact Infobip: For specific throughput questions or optimization

API endpoint for campaign details:

• GET /campaigns/1/campaigns/{campaignId} - Retrieve campaign details including status
• See USA Number Registration API reference for complete documentation

Improving toll-free throughput

If your toll-free number is rate-limited and you need higher throughput:

Option 1: Use multiple toll-free numbers [#option-1-use-multiple-toll-free-numbers-improving-toll-free-throughput]

If your use case allows, you can register multiple toll-free campaigns using different numbers. Throughput limits apply per number, so distributing traffic across numbers increases total throughput.

Example:

• 1 toll-free number: approximately 5 messages per second
• 3 toll-free numbers: approximately 15 messages per second (distribute traffic evenly)

Considerations:

• Each number requires separate registration
• Customers see different caller ID for each number
• May increase brand confusion; not recommended unless necessary

Option 2: Migrate to short code [#option-2-migrate-to-short-code-improving-toll-free-throughput]

For high-volume messaging, short code provides significantly higher throughput:

Short code throughput:

• AT&T: 50-more than 100 messages per second
• T-Mobile: 50-more than 100 messages per second
• Verizon: 50-more than 100 messages per second

Trade-offs:

• Higher cost ($500 to more than $1,000 per month)
• Longer setup (4 to 6 weeks)
• Requires certification
• Better for marketing-focused messaging

See Understanding short code for complete details.

Option 3: Optimize message distribution [#option-3-optimize-message-distribution-improving-toll-free-throughput]

For event-driven or notification messaging, optimize distribution across time:

• Spread notifications: Do not send all at once; spread over minutes/hours if possible
• Use scheduled delivery: Queue messages for optimal delivery windows
• Implement backoff: Reduce sending rate if delivery queue builds up

Error codes related to throughput

When toll-free messages are throttled or queued, you may receive these responses:

See Campaign rejection error codes reference for comprehensive error code guidance.

Best practices for toll-free throughput

Toll-free for two-way messaging

Toll-free excels at two-way customer communication:

Inbound SMS handling:

• Customers can text your toll-free number
• Messages flow to your system through webhooks
• Response messages (MT) rate-limited as described above

Advantages:

• Lower setup complexity than short code
• No certification required
• Customers recognize 800/888 format
• Perfect for support and service interactions

For complete two-way setup, see:

• Get started with toll-free - Full operational guide
• Understanding toll-free - Concepts and use cases

Learn more

• Understanding toll-free. Toll-free concepts and when to use
  
• Get started with toll-free. Complete setup guide
  
• Understanding short code. When to use short code instead
  
• 10DLC throughput reference. 10DLC carrier limits for comparison
  
• USA SMS compliance requirements. Compliance rules