APP for our CRM Vtiger PBX to make calls.

I have not used vtiger CRM before, but they offer a Zapier integration ( https://zapier.com/zapbook/vtiger/ ) and RingCentral was just released in beta for Zapier as an integration as well. If vTiger has the Trigger you want to use in Zapier, you could have the next step in your ZAP to use the RingOut Action of RingCentral's zapier integration to make the call for you. This might need some experimentation, but it should be possible.