As @Saqqara mentioned, try from a different IP address, if you're using your WiFi, try log in using the browser on your phone using your mobile internet connection. You can also use a VPN if you use any, it'll allow you to try again.
If you're unable to connect via a new connection (different IP) using a mobile device using 3G / 4G etc, and you're only allowed to use the work WiFi, then you'll need to wait until the IP Blacklist timeout has been reached:
By default this is set to 86400 seconds or 24hrs.
As we do not administer your PBX, we're unable to unlock it on your behalf.