If you’re experiencing spam or phantom incoming calls that appear as “blocked” or CLIs such as 100 you are probably the victim of a form of malicious attack. In summary they come in two forms:
- An overseas call centre has your number and while unwanted is making genuine calls which often display the CLI as ‘blocked’. As your carrier, we will quickly block these calls once advised by you after we confirm the originating source.
- A port scan into port 5060 is actually a form of attack to your router for those customers connecting over the public internet using ‘Peering’ or alternately ‘Registration’ with port forwarding to port 5060 but importantly missing the appropriate firewall rules. As attacks like this do not come via our network they don’t show in your CDR record.
These calls can be dangerous, as they are attempts to enter your PBX, then route calls back out through your CloudPBX account to selected and expensive destinations across Asia, Africa and parts of eastern Europe. Our strong advise is to quickly “lock down” your device with the appropriate firewall rule on SIP port 5060.