Fail2ban is currently used for SSH and NGINX. It can still be used for FreeSWITCH, but it's not by default for new installs.
Years of experience using fail2ban with FusionPBX have resulted in many false positives blocking legitimate traffic. Fail2ban has helped and harmed almost everyone who has used FusionPBX. If using Fail2ban for FreeSWITCH, I recommend whitelisting all client IP addresses. Unfortunately, Fail2ban should have the ignoreip addresses in one file, but this is not the case. Instead, each one has to be added to one continuous line. Whitelisting IP addresses in Fail2ban can and should be handled better. Also, on a busy server, Fail2ban can take a lot of CPU to read the logs.
Event Guard is a better tool for protecting FreeSWITCH than Fail2ban. Anything in Access Controls that is set to allowed is whitelisted for Event Guard. I need to work on some other things right now, so I'm not going to explain all the benefits of Event Guard. I built Event Guard because of multiple frustrations with Fail2ban.