I have been getting calls at a work phone from 201 298-6979. On the phone display it says "VONAGE", so I googgled the number and found all kinds of complaints about people getting called.
So today, I called the "real" Vonage 800 number and told them what's been happening. They searched their customer database, and they said they don't own that number, neither for the company or for their customers. So my conclusion is: it's a SCAM! And Vonage is taking the blame for it.
Vonage suggested I call my phone provider and have them block that number.
Just the same with us, mute calls from 2012986979 at odd hours. Caller ID on the phone says it´s from Vonage.