VOIP Phone receiving ghost calls.

I am hoping someone here can help me. I have a ZyXel router modem model # VMG4381.B10A provided by Cincinnati Bell for Fioptic internet service. My phone system is a VOIP system by 8x8. Since Cincinnati Bell installed the  ZyXel modem router I am receiving "ghost calls" constantly. I spent a couple of days on the phone with 8x8. The VOIP phone is plug-n play and configured properly. I then spoke with Cincy Bell who tried a number of things which did not work. They said a bridge was needed however they no longer bridge modems.  So I'm stuck and the constant calls are driving me crazy.  I did not have this issue with TWC cable mo dem. Can anyone here help or point me in the right direction?

#CPE_December