I see a lot of unknown calls in statistics

You see a lot of unknown calls in your statistics with unusual destinations and callerIDs.

• First of all check if Fail2Ban is installed

You should see such lines after issuing command iptables --list :

[root@kolmisoft]# iptables --list
Chain INPUT (policy ACCEPT)
target     prot opt source               destination         
DROP       all  --  XX.XX.XX.XX         anywhere            
fail2ban-SSH  tcp  --  anywhere             anywhere            tcp dpt:ssh 
fail2ban-ASTERISK  all  --  anywhere             anywhere            
DROP       all  --  XX.XX.XX.XX       anywhere            
DROP       all  --  XX.XX.XX.XX  anywhere      

Where XX.XX.XX.XX is some IP address

• If you see unauthorized calls from your connected PBX like FreePBX, Elastix:

1. Make sure you use strong passwords for authentication
2. Check if there are unauthorized connections in PBX
3. Block all unknown IPs from your system
4. In some cases external PBX'es were hacked, related problems are reviewed here, here and here.
5. Setup a secure VPN connection from your PBX to MOR.