Calls per second (CPS) refers to limits on your account for sending and receiving calls. The limits differ for outbound and inbound calling. By default, we assign an outbound CPS limit of 2 and an inbound limit of 10 at signup time. You can find your allocated inbound and outbound CPS by visiting the Voice Overview page of Plivo console and looking in the Account section.
For outbound calling, CPS represents a limit on the rate at which calls are initiated for a specific account. Outbound CPS applies only to calls made using APIs; it does not apply to calls made using the Dial XML element.
If you exceed your allotted outbound CPS, your calls will not be dropped; instead, they will be queued and dispatched once the CPS rate falls below the limit.
You can maintain as many concurrent calls as your servers permit, but the rate at which calls are placed adheres to the allocation in your account. Here are a couple of examples.
Scenario 1: If a user has an allocated outbound limit of 10 CPS and places 10 API calls in a second, all 10 calls will be executed simultaneously.
Scenario 2: If a user has an allocated outbound limit of 10 CPS and places 12 API calls in a second, the first 10 calls will be executed simultaneously, and the remaining two calls will be queued and executed during the next available CPS interval.
For inbound calling, CPS represents a limit on the rate of inbound calls to Plivo numbers, and also to the rate of outbound calls originating from SIP and browser clients. (The term "inbound CPS" is used because outgoing call requests from SIP and browser clients are essentially inbound requests to Plivo.) Calls that surpass the specified inbound CPS limit based on the above criteria are rejected with SIP code 486.
Can I increase my allocated CPS?
If you have a use case that requires a higher CPS limit, contact the Plivo support team.