Spam ghost calls

[arczi]

Hi,

Two days ago our client reported to us spam ghost calls issue.
Basically there is phone call every 7/8 minutes, which destination is always the same extension - 818 (872 is called because of forwarding rules). When the call is picked up, nobody is responding.
Two days ago the external number calling was 102 so I blocked it. Yesterday the number changed to 1002 - blocked as well.
Today the number changed to 10002.
Is there any way to block the caller using different method than blocking specific number?
I'm afraid the number is going to change every day. I know I can block numer 1*2 but what if it changes to 103 for example?

Regards.

 

[Alphabetic]

Are you using supported 3CX phones with the default templates and latest firmware?

 

[akakern95]

You probably are missing a firewall rule for port 5060 PBX side.
You should only allow traffic to port 5060 from your SIP provider, otherwise you get ping calls by random attackers.