FYI.
The IP addresses are listed on the VoIPBL IP blacklist but don't appear to be listed on any others, nor do the subnets as a whole.
We use a variety of IP Blacklists, the most useful being VoIPBL.
If your firewall supports it the IP blacklists could be applied to protect your entire infrastructure updating every hour, if not you can build a simple bash script for your servers to update your IP tables.
Shaun
