Hi,
First sorry if my English is not perfect.
I work for many operators as consultant and since some time on security issue.
I can say for sure that first step is:
allowguest=no
Second thing I have noticed that most of time good hackers don’t registers and send call without registering
disalowing call without registration is also a good way to prevent hacking.
Recently I have noticed that Hackers use online sip device hacking, this is more easy than hacking server
I have noticed that Audiocode gateway are the number one target
I’ts easy to find with scanner with Allegro-Software in port 80 resolving
and this device have a serious security problem.
You can use my tool online to check if you have one online
comdif.com/get.php
There is usualy two target for sip hacking
1 -Make a night termination
2 -Send maximum calls to a premium number
The second one is 90%
And my proposal is to make a general online db containing all these numbers and imput
DB check on each dial feature.
For example these numbers pncall.com/test-numbers.html
must be blacklisted.