The RingCentral app allows you to make and receive multiple calls, view and manage all the ongoing active calls, and handle each of them as needed. You can make or receive up to nine calls without ending the call you're already on.
If you’re already handling nine calls, more incoming calls will be routed to other endpoints. For example, to your RingCentral mobile app. If you try to make more outbound calls, the app will notify you that you've reached the maximum calls limit.