P-Series Cloud and Software versions don't allow you to run tcpdump at the command line but you can use the pjsip logger to get realtime logs at the command line.

At the command line enter the Asterisk console

asterisk -r

Then you can set the SIP logger on/off and log to file or view in realtime

pjsip set logger on

IP addresses will be private and won't reflect your public IPs as the PBX is behind an SBC.

HINT: exit the Asterisk console if you want to scroll up your terminal to see events otherwise updates to your screen will keep auto-scrolling you.