Call Concurrency Limits

Overview

Sulus enforces call concurrency limits to ensure reliable compute for all customers. Every account starts with a default allocation, and you have several options to monitor, manage, and increase that limit as your usage grows.

Every Sulus account includes 10 concurrent call slots by default. Each active call occupies one slot — when all slots are busy, new outbound dials or inbound connections wait until a slot becomes free.

• Inbound agents rarely hit concurrency caps unless traffic surges (e.g., launches, seasonal spikes)
• Outbound agents are more likely to reach limits when running large calling batches

Outbound campaigns: Batch long lead lists into smaller chunks (e.g., 50–100 numbers) and run those batches sequentially to stay near the default limit while still processing large sets.

High-volume operations: If you regularly exceed 50,000 minutes per month, Sulus offers custom plans with higher baked-in concurrency, and add-on bundles to purchase extra call lines only when needed.

You can raise your limit directly from the dashboard without contacting support:

1. Open the Sulus Dashboard
2. Navigate to Settings → Billing
3. Find Reserved Concurrency (Call Lines)
4. Increase the limit or purchase add-on concurrency lines

Changes apply immediately, so you can scale ahead of known traffic surges.

When you create a call with POST /call, the response includes a subscriptionLimits object:

{
  "subscriptionLimits": {
    "concurrencyBlocked": false,
    "concurrencyLimit": 10,
    "remainingConcurrentCalls": 9
  }
}

Use the /analytics endpoint to review historical concurrency usage and identify patterns that justify more capacity. You can adjust timeRange.step to inspect usage by hour, day, or week.

Note: concurrency limits are on the Sulus side. Your telephony provider may have separate rate limits of its own.

In summary, Sulus's default 10-slot concurrency limit is sufficient for most use cases, but outbound campaigns at scale may require batching strategies or a plan upgrade. You can monitor your usage in real time via the API response fields and historically via the Analytics API, and increase your limit directly from the billing settings.