Strange calls

I am getting strange calls on one of my extensions. The numbers displayed in the caller ID are always something simple like “1234”, “100”, or “111”. When I pick up the phone, there is no one on the other end? I get twenty of these calls a day. Is this some sort of SPAM? How do I stop it?

I suspect this might have nothing to do with FreePBX or ASterisk because I do not see anything in the log when I get these calls.

Configuration: Cloud-based FreePBX 1.816.210.58-1, Yealink T26P connected using SIP

Is your Yealink “exposed” to the Internet ?

Check your call logs very carefully. You may have been hacked. This is a classic symptom of phone system probing.

I’m not sure if it is exposed. It is communicating with my FreePBX server, which is out on the Internet, but it does that by calling out through SIP. The phones are sitting behind my router.

Nothing shows up in my Asterisk call logs.

I asked already.

Is your Yealink “exposed” to the Internet ?

I ask that because if it is then there are many “vectors” that will attack your responding endpoint as much as they attack our servers that answer on udp 5060 without proper firewalls.

If your FreePBX server is on the Internet then 5060 must be open to some extent. How is this secured? Can you check the server and look for the file /etc/sysconfig/iptables and see what is set in here for udp port 5060.