This is traffic from sipvicious. It’s an auditing and testing tool for SIP (but of course bad guys also like to use it to find vulnerable accounts or servers).
So if it’s not yourself who is playing around here with that tool, you should harden your network and your asterisk server.
The other alternative is if you’re using the PBX internally and only have outside trunks coming in, lock your firewall to those trunk IPs. So like 5060 on my connection will only talk to my provider’s server and no one else.