This page covers concurrency limits specific to India. For global account limits (CPS, API rate limits, feature limits), see Account and feature limits.
- Default concurrency limit: 50 concurrent calls
- What counts: All PSTN calls (inbound and outbound, across Voice API and SIP trunking)
- CPS relationship: CPS = concurrency limit ÷ 25 (default 2 CPS)
- Exceeding the limit: Calls are rejected instantly — no queuing, no grace period
- To increase: Raise a ticket with Plivo support
Hard enforcement is active from April 20, 2026. Calls that exceed your concurrency limit fail instantly with no queuing or grace period. Review your usage and increase your limit if needed.
What Is Concurrency?
Concurrency is the number of active calls at any given point in time. This includes calls in all active phases — not just fully connected calls.
| Call State | Description | Counted? |
|---|
| Ringing / Connecting | Call initiated and in the setup phase | Yes |
| Connected / In-progress | Call is live and voice is flowing | Yes |
| Completed / Ended | Call has been disconnected | No |
How Your Limit Works
Your account has a default concurrency limit of 50 concurrent calls. CPS (Calls Per Second) is derived from your concurrency limit:
CPS = Concurrency Limit ÷ 25
For example, an account with a concurrency limit of 100 has a CPS of 4 (100 ÷ 25).
| Concurrency Limit | CPS |
|---|
| 50 (default) | 2 |
| 100 | 4 |
| 250 | 10 |
| 500 | 20 |
Both limits apply simultaneously. The concurrency limit caps how many calls can be active at once. CPS caps how fast you can start new calls.
What Happens When You Exceed the Limit
When your active call count reaches the concurrency limit, any new call attempt is rejected immediately.
| Scenario | Outcome |
|---|
| Call attempt while under limit | Call proceeds normally |
| Call attempt that would breach limit | Call fails immediately — no ring, no connection |
| Subsequent calls while at the limit | Continue to fail until active calls drop below the concurrency limit |
| Recovery | As soon as active calls drop below the concurrency limit, new calls are accepted again |
There is no queuing and no grace period. Calls are rejected the moment they would breach the limit.
Error Codes
| Product | Code | Reason |
|---|
| Voice API | 5030 | Concurrency Limit Breached |
| Zentrunk | 5190 | concurrent_call_limit_exceeded |
5030 is returned in two places:
- API response — returned immediately when the call attempt is rejected
- Hangup URL callback — delivered to your hangup URL
How to Check Your Usage
You can view concurrency data directly from the Plivo console:
- Navigate to Voice > Call Logs > Export > Export Concurrency Data.
- The export provides minute-level concurrent call data for up to 30 days.
Rule of thumb: If your 30-day peak concurrent call count exceeds 80% of your concurrency limit, we recommend reviewing your capacity and increasing your limit before you experience call failures.
Recommendations to Manage Concurrency
Follow these best practices to avoid hitting your concurrency limit unexpectedly:
-
Monitor your peak usage regularly. Export concurrency data from the Plivo console and review your 30-day peak. If your peak exceeds 80% of your limit, consider increasing your limit.
-
Stagger outbound campaigns. If you run bulk outbound calls, spread them over time rather than launching all at once. This keeps your concurrent call count well below the limit.
-
Handle errors gracefully. When a call is rejected with error code 5030, implement retry logic with a short delay. Wait for active calls to complete before retrying.
-
Optimize call duration. Shorter calls free up concurrency slots faster. Review your call flows to ensure calls are not staying connected longer than necessary.
-
Plan for traffic spikes. If you expect seasonal or event-driven traffic increases, increase your concurrency limit in advance by raising a ticket with Plivo support.
How to Increase Your Limit
To increase your concurrency limit, raise a ticket with Plivo support. Your CPS adjusts automatically — every additional 25 concurrent call slots adds 1 CPS.
| Detail | Value |
|---|
| What changes | Your account’s concurrency limit |
| Minimum increment | 25 concurrent call slots (adds 1 CPS) |
| How to request | Raise a ticket with Plivo support |
FAQ
My usage sometimes spikes — what should I do?
Review the 30-day peak in your concurrency export to understand worst-case scenarios. If your peak is close to your limit, add a safety buffer by increasing your concurrency limit to avoid call failures during traffic spikes.
How do concurrency and CPS relate?
CPS is derived from your concurrency limit. For every 25 concurrent call slots, you get 1 CPS. Both limits apply simultaneously — concurrency caps how many calls can be active at once, and CPS caps how fast you can start new calls.
