Call Log with asterisk in both source and CLID columns

Sorry to have to post on what is hopefully an easy question but searching for “asterisk” in call logs is not to fruitful.
To restate, occasionally in my call logs report there appears a line with asterisk in the Source and Clid columns.

I was wondering what this is?

The duration is between 16 and 18 seconds. destination is s and disposition is answered.
most curiously the channel is SIP/


Someone from Asia is trying to hack your PBX.
Make sure that all your extensions are with good passwords otherwise change them immediately.


I saw this same phenomenon on my PBX, I had already strong passwords. There is even 2 times tried, but failed.

Do I need for these attacks beyond the fact that I have to use strong passwords Another precaution to take?