Firewall Question

I was looking through my Asterisk logfile and noticed numerous entries like the following:

[2017-04-11 16:34:02] NOTICE[12982] res_pjsip/pjsip_distributor.c: Request 'OPTIONS' from '"sipvicious" <sip:[email protected]>' failed for '' (callid: 796122216689497066538755) - No matching endpoint found

This would appear to be someone trying to hack our server. We have a Meraki firewall infront of our FreePBX server with SIP ports forwarded for remote access. We are using the FreePBX responsive firewall and IDS. Should I be concerned with log entries like the one above?