It depends on which jail is blocking you.
Code:
fail2ban-client set <jail> unbanip <ip>
fail2ban-client set sshd unbanip 1.2.3.4
If the version of FusionPBX you are using still uses iptables then you will be able see a list of firewall rules with the following command:
Look for your IP address in the output and that may give you a clue as to where you are being blocked.