Router changed to XB7 now alarm can't dial out

So my router was upgraded at Comcast's urging from the XB6 black to XB7 white.  My alarm performs a test where it communicates with the central station.  Once the routers changed, the alarm can no longer communicate.  The phones however work fine.  The alarm guy thinks that the XB7 Xfinity Voice service is limiting the single that the alarm communication needs to dial out.  Ideas?