I have been getting so many spam calls that I’ve not been picking up my phone

Our Evolve phone system seems to just run great but there is a matter that I’d like you to be aware of. Our CST Oak Brook, Il DID lines have been getting spammed with robo calls. I just spent an hour on the phone with Derrick in Evolve support and we were able to determine that a lot of the calls seem to be originating from 4.55.xxx.xxx IP address. However the last octets of that IP group keep changing as well as the numbers that they are calling from. I have been getting so many spam calls that I’ve not been picking up my phone. Is there a solution is issues like this other than leave the phone off of the hook?
Thanks
Pete