The version of snort on the appliance is relatively out of date, so it's possible it's not properly detecting what you'd expect. You can either tune the rule to exclude that system, or disable the rule.
You should probably be able to follow a process similar to this one to get the rules and tweak them - SolarWinds Knowledge Base :: How to tune Snort to address the "COMMUNITY SIP TCP/IP message flooding directed to SIP pro…
But in the long term it might be more ideal to offload snort and have a) a more recent version and b) better/quicker access