We have done VoIP integrations in the past. We generally do these for things like screen pop (someone calls and based on caller ID, we pop the associated QuickBase record or records). RingCentral does have a very flexible SDK/API. We would be happy to talk to you further about this. Feel free to reach out to us at www.mcftech.com.
Trinity has recently developed a QuickBase integration with the RingCentral VoIP solution. Inbound calls open the associated Contact record (or ticket or whatever you want us to tie it to) in your QuickBase app. Outbound calls can be initiated right from your QuickBase app and dial using RingCentral. If you are still looking please get hold of me at firstname.lastname@example.org