How many calls can I create per second?

Question

What is the maximum number of calls per second allowed?

Applies To

• SIP Trunking
• Voice API
• Outbound Calls

Answer

There is no limit to the concurrent capacity of calls for your account, and the limitation is only for calls per second.

The maximum throughput is 3 calls per second (CPS). If you initiate SIP calls at a faster rate, the call will be rejected, and will not be queued. You would need to lower your call initiation rate and retry the rejected call.

This throughput limit is shared across all Voice products for all types of outbound call, including PSTN, SIP Trunking, WebSocket, and In-App Voice.

If you have a secondary API key, the CPS will also be 3, but will be limited by the primary API key as a global CPS at the same time. 

Examples

• 2x calls using the secondary API key and 1x using the primary API key will reach the 3 CPS limit for the primary API key, and subsequent calls in the same second would be rejected.
• 3x calls created using the primary API key would use the global CPS, and any additional calls created using the primary or secondary API key in the same second would be rejected.

• 1x call using the primary API key and 1x call using the secondary API key would be a global CPS of 2, with capacity to create 1x additional call using either API key within the same second.

   

If your throughput exceeds this threshold using the Voice API, you will receive HTTP response error code 429, and your request will not be queued. You would need to lower your sending rate and retry the request.

Virtual Numbers

Virtual numbers may have their own independent concurrent capacity for inbound calls, depending on the limitations of the local supplier or network.

Additional Information

For information on inbound voice capacity, see Inbound Voice Restrictions, Features and Capacity.

If you have a business need for higher call throughputs, contact your account manager.