There is a default limit to your Calls Per Second (CPS) allowance. CPS indicates the number of calls that can be initiated every second. By default, each account can initiate one call per second. Please contact the Plivo Sales Team if you need a higher CPS for your account. The CPS limit applies to outbound calling.
There are no limitations to the number of concurrent calls you can make using Zentrunk. Zentrunk servers are elastic in nature. These servers can scale up or down depending on call traffic. No additional configurations are required to add more capacity.
Since Zentrunk SIP trunks are charged on a pay-as-you-go basis, you are only charged for the minutes you use.