I'm a new user and have been receiving calls about once a day without CID, but with CNAM of ASTERISK. These are not real calls and there is no caller or record in the call detail register. My configuration is:

HT502 Port 1 on Voipo, Port 2 on VoIP.ms. Only port 1 receives these calls
I'm behind a firewall router with ports 5000-6500 forwarded to the IP of the ATA
Using port SIP port 5060 for port 1 and 5062 for port 2. Just changed the HT502 to use random ports.

Only the VoiPo line receives the calls the VoIP.ms line has not been affected. I have two services so that I have redundant operation, having learned to not put all of the service in one basket.
Any suggestions on how to stop these random ASTERISK calls?