India telephony operates on a concurrency (channels) model. Your account has a maximum number of calls that can be active simultaneously, and calls that exceed this limit are rejected immediately.
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 upgrade your CPS 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 |
| Product | Counted? |
|---|
| Voice API | Yes |
| Zentrunk | Yes |
How Your Limit Is Calculated
Your concurrency limit is derived from your account’s outbound CPS (Calls Per Second) allocation:
Concurrency Limit = Outbound CPS × 25
For example, an account with an outbound CPS of 4 has a concurrency limit of 100 concurrent calls (4 × 25).
| Outbound CPS | Concurrency Limit |
|---|
| 2 (default) | 50 |
| 4 | 100 |
| 10 | 250 |
| 20 | 500 |
CPS limits remain unchanged. The concurrency limit is an additional constraint layered on top of CPS. Both limits apply simultaneously.
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 over limit | Continue to fail until active calls drop below the limit |
| Recovery | As soon as active calls drop, 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 | Cause |
|---|
| Voice API | 5030 | Concurrency Limit Breached |
| Zentrunk | 5190 | concurrent_call_limit_exceeded |
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.
80% threshold rule: If your 30-day peak concurrent call count exceeds 80% of your concurrency limit, review your capacity and consider upgrading before you experience call failures.
How to Upgrade
To increase your concurrency limit, you must increase your CPS allocation. Each additional 1 CPS grants 25 more concurrent call slots.
| Detail | Value |
|---|
| What is upgraded | Your account’s outbound CPS limit |
| What each +1 CPS grants | 25 additional concurrent call slots |
| 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 upgrading your CPS to avoid call failures during traffic spikes.
Does the concurrency limit affect my CPS limit?
No. CPS limits remain unchanged. The concurrency limit is an additional constraint layered on top of CPS. Both limits apply simultaneously.
