Unblock an IP
Accidents happen and now your restricted from your server or PBX, let's fix it.
find out which IP's are being blocked determine if this is your issue
There are a couple of ways:
iptables -L -n --line-numbers
Assuming your being blocked by the "Asterisk Jail" unblock your IP with this:
fail2ban-client set asterisk-iptables unbanip your.ip.address