Can I make multiple calls at the same time with Voice API?
It is not possible to send an API request with multiple recipient handsets, and an API request must be made to each recipient. If you are using a Connect action, you can include multiple Connect actions within the same NCCO and all of the recipients will be called in turn as the NCCO is processed. You can make outbound Voice API requests at a rate of 3 requests per second, so you will be able to create 3 calls per second using an API request. Multiple inbound callers can access the same NCCO at the same time, and the restriction is based upon the concurrent call limit for the inbound virtual number.