Use AirPods with the Vonage Phone service on my Mac I use the Vonage service to make calls from my MacBook Pro for business, both outgoing and incoming. My Mac shows the AirPods as connected but if I try to make a call, the sound still comes out of the internal speaker on my Mac. 

Does anyone kn ow how I might fix this? Perhaps I need to adjust the internal microphone somehow? 

I've already set the AirPods as both the Input and Output for sound.
If the headphones work with FaceTime and other audio apps then you can conclude the program you’re using for Vonage need some set up or you need to find a different program that respects the capabilities of macos to switch between multiple sound in and out options. 

You have done all you can by using the sound preference pane to select a  choice and it’s up to the third-party software to respect your choices.