Calls with "S" destination every minute exactly


I hope you are doing great.

I have an Asterisk PBX system and two weeks ago our telephone service providers reported that we had an excesive traffic.

We check CDR reports and we found a lot of calls with “s” destination every minute exactly. We are trying everything to stop that, all access from WAN to LAN is closed (SIP, SSH, UDP), access from VPN to LAN is allowed because we work over VPN’s.

Also, “allow anonymous calls” and “allow SIP guests” are set to “NO”, but nothing is working for us, the problem persists. We need to solve this issue ASAP.

Any suggestion to fix the problem?

I hope you can help us. Thanks in advance.

Best regards.


what shoes in the cli and try … wireshark/

and use cloudshark or wireshark to find out where its coming from and block it.

On the CDR you can see the source that it is originating the call to the S extension that could help you to control the traffic too. and why not estabish a call rule filter in the dial plan

Or better yet…how about locking down your PBX so it doesn’t get exploited and you get a $15K phone bill for calls to Cuba.

Security is paramount on IP PBX phone systems. Especially open source. Keep it up to date.