bypassing the hotspo login page

Hi guys, pls i will like to know how to bypass a mikrotik hotspot login page.. I understand a little about the technology.. the Radius server authentification and the redirection to the gateway bla bla bla.. my question is i need more clues to bypassing the login page..

I presently manage an ISP, and someone not registered is always on my network.. Using the network for free.. Pls guys i need yourt help. I really want to know how he byepass it then i can improvoe on my security also.

my email adress is adepetu2000@yahoo.co.uk

I await your response and assistance.

thanks
Engr Emmanuel