Asterisk by default use 5060 as its SIP signaling port. It is a good idea to change the default SIP port as most of the SIP vulnerable attacks occurs on it’s default port 5060.
To change the SIP port, open /etc/asterisk/sip.conf in your favorite text editor, look for the entry bindport and change the value of it to your new port number. If you didn’t find the bindport entry in your sip.conf file, add the below line under the [general] section inside sip.conf
i.e., if you want to change the port number to 5080, add the line as
bindport = 5080
Reload your asterisk configuration to make the changes active. Use the below command to check if the changes are active and SIP listens on the new port number
netstat -ntulp | grep portnumber
example : netstat -ntulp | grep 5080
If you see an output for the above command, then the changes are active and SIP now listens on new port number.